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{{good article}}
{{otheruses4|the branch of mathematics}}
{{Short description|Branch of mathematics}}
{{Use mdy dates|date=August 2024}}
{{About||the kind of algebraic structure|Algebra over a field|other uses}}
{{multiple image
|perrow=1 / 1
|total_width=350
|image1=Polynomial2.svg
|alt1=Polynomial equation
|link1=Polynomial equation
|caption1=[[Elementary algebra]] studies which values solve equations formed using arithmetical operations.
|image2=Ring of integers2.svg
|alt2=Signature of the ring of integers
|link2=Ring of integers
|caption2=[[Abstract algebra]] studies [[algebraic structure]]s, such as the [[ring of integers]] given by the set of [[integer]]s <math>(\Z)</math> together with [[Algebraic operation|operations]] of [[addition]] (<math>+</math>) and [[multiplication]] (<math>\times</math>).
}}


'''Algebra''' is the branch of [[mathematics]] that studies certain abstract [[system]]s, known as [[algebraic structures]], and the manipulation of statements within those systems. It is a generalization of [[arithmetic]] that introduces [[Variable (mathematics)|variables]] and [[algebraic operation]]s other than the standard arithmetic operations such as [[addition]] and [[multiplication]].
'''Algebra''' is a branch of [[mathematics]] concerning the study of [[structure (algebraic)|structure]], [[relation (mathematics)|relation]], and [[quantity]]. The name is derived from the treatise written by the [[Persian people|Persian]]<ref>See the references Toomer, Hogendijk 1998, Oaks cited in the article on [[Muhammad ibn Mūsā al-Khwārizmī|{{Unicode|al-Khwārizmī}}]].</ref> [[Islamic mathematics|mathematician]], [[Islamic astronomy|astronomer]], [[Islamic astrology|astrologer]] and [[geographer]], [[Muhammad ibn Mūsā al-Khwārizmī|{{Unicode|Muhammad bin Mūsā al-Khwārizmī}}]] titled ''Kitab '''al-Jabr''' wa-l-Muqabala'' (meaning "''[[The Compendious Book on Calculation by Completion and Balancing]]''"), which provided symbolic operations for the systematic solution of [[linear equation|linear]] and [[quadratic equation]]s, and recognized algebra as an independent discipline. Al-Khwarizimi's book made its way to Europe and was translated into Latin as ''Liber algebrae et almucabala''.


[[Elementary algebra]] is the main form of algebra taught in school and examines mathematical statements using variables for unspecified values. It seeks to determine for which values the statements are true. To do so, it uses different methods of transforming equations to isolate variables. [[Linear algebra]] is a closely related field investigating variables that appear in several [[linear equation]]s, called a ''[[system of linear equations]]''. It tries to discover the values that solve all equations in the system at the same time.
Together with [[geometry]], [[mathematical analysis|analysis]], [[combinatorics]], and [[number theory]], algebra is one of the main branches of [[mathematics]]. [[Elementary algebra]] is often part of the curriculum in [[secondary education]] and provides an introduction to the basic ideas of algebra, including effects of [[addition|add]]ing and [[multiplication|multiply]]ing [[number]]s, the concept of [[variables]], definition of [[polynomial]]s, along with [[factorization]] and determining their [[root (mathematics)|root]]s.


[[Abstract algebra]] studies algebraic structures, which consist of a [[Set (mathematics)|set]] of [[mathematical objects]] together with one or several [[Operation (mathematics)|operations]] defined on that set. It is a generalization of elementary and linear algebra since it allows mathematical objects other than numbers and non-arithmetic operations. It distinguishes between different types of algebraic structures, such as [[Group (mathematics)|groups]], [[Ring (mathematics)|rings]], and [[Field (mathematics)|fields]], based on the number of operations they use and the [[Axiom|laws they follow]]. [[Universal algebra]] provides a general framework to investigate abstract patterns that characterize different classes of algebraic structures.
Algebra is much broader than elementary algebra and can be generalized. In addition to working directly with numbers, algebra covers working with [[symbols]], variables, and [[set]] [[element (mathematics)|elements]]. Addition and multiplication are viewed as general [[operator|operations]], and their precise definitions lead to structures such as [[group (mathematics)|groups]], [[ring (mathematics)|rings]] and [[field (mathematics)|fields]].


Algebraic methods were first studied in the [[ancient period]] to solve specific problems in fields like [[geometry]]. Subsequent mathematicians examined general techniques to solve equations independent of their specific applications. They described equations and their solutions using words and abbreviations until the 16th and 17th centuries, when a rigorous symbolic formalism was developed. In the mid-19th century, the scope of algebra broadened beyond a [[theory of equations]] to cover diverse types of algebraic operations and structures. Algebra is relevant to many branches of mathematics, such as geometry, [[topology]], [[number theory]], and [[calculus]], and other fields of inquiry, like [[logic]] and the [[empirical sciences]].
== Classification ==
Algebra may be divided roughly into the following categories:


== Definition and etymology ==
* '''[[Elementary algebra]]''', in which the properties of operations on the [[real number|real number system]] are recorded using symbols as "place holders" to denote [[constant]]s and [[variable]]s, and the rules governing [[mathematical expression]]s and [[equation]]s involving these symbols are studied (note that this usually includes the subject matter of courses called ''intermediate algebra'' and ''college algebra''), also called second year and third year algebra;
Algebra is the branch of mathematics that studies [[algebraic structure]]s and the [[algebraic operations|operations]]{{efn|When understood in the widest sense, an algebraic operation is a [[function (mathematics)|function]] from a [[Cartesian product#n-ary Cartesian power|Cartesian power of a set into that set]], expressed formally as {{nowrap|<math>\omega: A^n \to A</math>.}} Addition of real numbers is an example of an algebraic operation: it takes two numbers as input and produces one number as output. It has the form {{nowrap|<math>+: \R^2 \to \R</math>.<ref>{{harvnb|Baranovich|2023|loc=Lead section}}</ref>}}}} they use.<ref>{{multiref | {{harvnb|Merzlyakov|Shirshov|2020|loc=Lead section}} | {{harvnb|Gilbert|Nicholson|2004|p=[https://books.google.com/books?id=paINAXYHN8kC&pg=PA4 4]}} }}</ref> An algebraic structure is a non-empty [[Set (mathematics)|set]] of [[mathematical object]]s, such as the [[real numbers]], together with algebraic operations defined on that set, like [[addition]] and [[multiplication]].<ref>{{multiref | {{harvnb|Fiche|Hebuterne|2013|p=[https://books.google.com/books?id=TqkckiuuXg8C&pg=PT326 326]}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ The Subject Matter of Algebra, Its Principal Branches and Its Connection with Other Branches of Mathematics.}} | {{harvnb|Gilbert|Nicholson|2004|p=[https://books.google.com/books?id=paINAXYHN8kC&pg=PA4 4]}} }}</ref> Algebra explores the laws, general characteristics, and types of algebraic structures. Within certain algebraic structures, it examines the use of [[Variable (mathematics)|variables]] in [[Algebraic equation|equations]] and how to manipulate these equations.<ref>{{multiref | {{harvnb|Pratt|2022|loc=Lead section, § 1. Elementary Algebra, § 2. Abstract Algebra, § 3. Universal Algebra}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ The Subject Matter of Algebra, Its Principal Branches and Its Connection with Other Branches of Mathematics.}} }}</ref>{{efn|Algebra is covered by division 512 in the [[Dewey Decimal Classification]]<ref>{{harvnb|Higham|2019|p=[https://books.google.com/books?id=ferEDwAAQBAJ&pg=PA296 296]}}</ref> and subclass QA 150-272.5 in the [[Library of Congress Classification]].<ref>{{harvnb|Library of Congress|p=3}}</ref> It encompasses several areas in the [[Mathematics Subject Classification]].<ref>{{harvnb|zbMATH Open|2024}}</ref>}}
* '''[[Abstract algebra]]''', sometimes also called ''modern algebra'', in which [[algebraic structure]]s such as [[group (mathematics)|groups]], [[ring (mathematics)|rings]] and [[field (mathematics)|field]]s are [[axiomatization|axiomatically]] defined and investigated; this includes, among other fields,
* '''[[Linear algebra]]''', in which the specific properties of [[vector space]]s are studied (including [[matrix (mathematics)|matrices]]);
* '''[[Universal algebra]]''', in which properties common to all algebraic structures are studied.
* '''[[Algebraic number theory]]''', in which the properties of numbers are studied through algebraic systems. [[Number theory]] inspired much of the original abstraction in algebra.
* '''[[Algebraic geometry]]''' in its algebraic aspect.
* '''[[Combinatorics|Algebraic combinatorics]]''', in which abstract algebraic methods are used to study combinatorial questions.
In some directions of advanced study, axiomatic algebraic systems such as groups, rings, fields, and algebras over a field are investigated in the presence of a [[geometry|geometric]] structure (a [[Metric (mathematics)|metric]] or a [[topology]]) which is compatible with the algebraic structure. The list includes a number of areas of [[functional analysis]]:
<div style="-moz-column-count:2; column-count:2;">
*[[Normed linear space]]s
*[[Banach space]]s
*[[Hilbert space]]s
*[[Banach algebra]]s
*[[Normed algebra]]s
*[[Topological algebra]]s
*[[Topological group]]s
</div>


Algebra is often understood as a generalization of [[arithmetic]].<ref>{{multiref | {{harvnb|Maddocks|2008|p=129}} | {{harvnb|Burgin|2022|p=[https://books.google.com/books?id=rWF2EAAAQBAJ&pg=PA45 45]}} }}</ref> Arithmetic studies operations like addition, [[subtraction]], multiplication, and [[Division (mathematics)|division]], in a particular domain of numbers, such as the real numbers.<ref name="auto1">{{multiref | {{harvnb|Romanowski|2008|pp=302–303}} | {{harvnb|HC Staff|2022}} | {{harvnb|MW Staff|2023}} | {{harvnb|Bukhshtab|Pechaev|2020}} }}</ref> [[Elementary algebra]] constitutes the first level of abstraction. Like arithmetic, it restricts itself to specific types of numbers and operations. It generalizes these operations by allowing indefinite quantities in the form of variables in addition to numbers.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=129–130}} | {{harvnb|Pratt|2022|loc=Lead section, § 1. Elementary Algebra}} | {{harvnb|Wagner|Kieran|2018|p=[https://books.google.com/books?id=uW4ECwAAQBAJ&pg=PT225 225]}} }}</ref> A higher level of abstraction is found in [[abstract algebra]], which is not limited to a particular domain and examines algebraic structures such as [[Group (mathematics)|groups]] and [[Ring (mathematics)|rings]]. It extends beyond typical arithmetic operations by also covering other types of operations.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=131–132}} | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} | {{harvnb|Wagner|Kieran|2018|p=[https://books.google.com/books?id=uW4ECwAAQBAJ&pg=PT225 225]}} }}</ref> Universal algebra is still more abstract in that it is not interested in specific algebraic structures but investigates the characteristics of algebraic structures in general.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 3. Universal Algebra}} | {{harvnb|Grillet|2007|p=[https://link.springer.com/chapter/10.1007/978-0-387-71568-1_15 559]}} | {{harvnb|Denecke|Wismath|2018|p=[https://books.google.com/books?id=2UlZDwAAQBAJ&pg=PR5 v]}} | {{harvnb|Cohn|2012|p=[https://books.google.com/books?id=6tbuCAAAQBAJ&pg=PR13 xiii]}} }}</ref>
== Elementary algebra ==


[[File:Image-Al-Kitāb al-muḫtaṣar fī ḥisāb al-ğabr wa-l-muqābala.jpg|upright=.8|thumb|alt=Title page of The Compendious Book on Calculation by Completion and Balancing|The word ''algebra'' comes from the title of [[al-Khwarizmi]]'s book {{transliteration|ar|[[Al-Jabr]]}}.<ref>{{multiref | {{harvnb|Cresswell|2010|p=[https://books.google.com/books?id=J4i3zV4vnBAC&pg=PA11 11]}} | {{harvnb|OUP Staff}} | {{harvnb|Menini|Oystaeyen|2017|p=722}} }}</ref>]]
{{main|Elementary algebra}}


The term "algebra" is sometimes used in a more narrow sense to refer only to elementary algebra or only to abstract algebra.<ref>{{multiref | {{harvnb|Weisstein|2003|p=46}} | {{harvnb|Walz|2016|loc=[https://www.spektrum.de/lexikon/mathematik/algebra/12062 Algebra]}} }}</ref> When used as a [[countable noun]], an algebra is [[algebra over a field|a specific type of algebraic structure]] that involves a [[vector space]] equipped with [[Bilinear map|a certain type of binary operation]].<ref>{{multiref | {{harvnb|Weisstein|2003|p=46}} | {{harvnb|Brešar|2014|p=[https://books.google.com/books?id=PkvPBAAAQBAJ&pg=PR33 xxxiii]}} | {{harvnb|Golan|1995|pp=[https://link.springer.com/chapter/10.1007/978-94-015-8502-6_18 219–227]}} }}</ref> Depending on the context, "algebra" can also refer to other algebraic structures, like a [[Lie algebra]] or an [[associative algebra]].<ref>{{harvnb|EoM Staff|2017}}</ref>
'''Elementary algebra''' is the most basic form of algebra. It is taught to students who are presumed to have no knowledge of [[mathematics]] beyond the basic principles of [[arithmetic]]. In arithmetic, only [[number]]s and their arithmetical operations (such as +, −, ×, ÷) occur. In algebra, numbers are often denoted by symbols (such as ''a'', ''x'', or ''y''). This is useful because:


The word ''algebra'' comes from the [[Arabic]] term {{lang|ar|الجبر}} ({{transliteration|ar|al-jabr}}), which originally referred to the surgical treatment of [[bonesetting]]. In the 9th century, the term received a mathematical meaning when the Persian mathematician [[Muhammad ibn Musa al-Khwarizmi]] employed it to describe a method of solving equations and used it in the title of a treatise on algebra, {{transliteration|ar|[[Al-Jabr|al-Kitāb al-Mukhtaṣar fī Ḥisāb al-Jabr wal-Muqābalah]]}} [''The Compendious Book on Calculation by Completion and Balancing''] which was translated into Latin as {{lang|la|Liber Algebrae et Almucabola}}.{{efn|The exact meaning of the term {{transliteration|ar|al-jabr}} in al-Khwarizmi's work is disputed. In some passages, it expresses that a quantity diminished by subtraction is restored to its original value, similar to how a bonesetter restores broken bones by bringing them into proper alignment.<ref>{{multiref | {{harvnb|Oaks|Alkhateeb|2007|pp=45–46, 58}} | {{harvnb|Gandz|1926|p=437}} }}</ref>}} The word entered the English language in the 16th century from [[Italian language|Italian]], [[Spanish language|Spanish]], and medieval [[Latin language|Latin]].<ref>{{multiref | {{harvnb|Cresswell|2010|p=[https://books.google.com/books?id=J4i3zV4vnBAC&pg=PA11 11]}} | {{harvnb|OUP Staff}} | {{harvnb|Menini|Oystaeyen|2017|p=722}} | {{harvnb|Hoad|1993|p=10}} }}</ref> Initially, its meaning was restricted to the [[theory of equations]], that is, to the art of manipulating [[polynomial equations]] in view of solving them. This changed in the 19th century{{efn|These changes were in part triggered by discoveries that solved many of the older problems of algebra. For example, the proof of the [[fundamental theorem of algebra]] demonstrated the existence of complex solutions of polynomials<ref name="auto7">{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Kvasz|2006|p=308}} | {{harvnb|Corry|2024|loc=§ The Fundamental Theorem of Algebra}} }}</ref> and the introduction of [[Galois theory]] characterized the polynomials that have [[solution in radicals|general solutions]].<ref name="auto2">{{multiref | {{harvnb|Kvasz|2006|pp=314–345}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Corry|2024|loc=§ Galois Theory, § Applications of Group Theory}} }}</ref>}} when the scope of algebra broadened to cover the study of diverse types of algebraic operations and structures together with their underlying [[axiom]]s, the laws they follow.<ref>{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Corry|2024|loc=§ Structural Algebra}} | {{harvnb|Hazewinkel|1994|pp=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA73 73–74]}} }}</ref>
* It allows the general formulation of arithmetical laws (such as ''a'' + ''b'' = ''b'' + ''a'' for all ''a'' and ''b''), and thus is the first step to a systematic exploration of the properties of the [[real number|real number system]].
* It allows the reference to "unknown" numbers, the formulation of [[equation]]s and the study of how to solve these (for instance, "Find a number ''x'' such that 3''x'' + 1 = 10").
* It allows the formulation of [[function (mathematics)|function]]al relationships (such as "If you sell ''x'' tickets, then your profit will be 3''x'' - 10 dollars, or ''f''(''x'') = 3''x'' - 10, where ''f'' is the function, and ''x'' is the number to which the function is applied.").


=== Polynomials ===
== Major branches ==
=== Elementary algebra ===
{{main|Polynomial}}
{{main|Elementary algebra}}


[[File:algebraic equation notation.svg|thumb|right|class=skin-invert-image|alt=Diagram of an algebraic expression|Algebraic expression notation:<br />&nbsp; 1 – power (exponent)<br />&nbsp; 2 – coefficient<br />&nbsp; 3 – term<br />&nbsp; 4 – operator<br />&nbsp; 5 – constant term<br />&nbsp; <math>c</math> – constant<br />&nbsp; <math>x</math> <math>y</math> – variables]]
A '''polynomial''' is an [[expression (mathematics)|expression]] that is constructed from one or more [[variable]]s and constants, using only the operations of addition, subtraction, and multiplication (where repeated multiplication of the same variable is standardly denoted as exponentiation with a constant whole number exponent). For example, <math>x^2 + 2x -3\,</math> is a polynomial in the single variable ''x''.


Elementary algebra, also called school algebra, college algebra, and classical algebra,<ref>{{multiref | {{harvnb|Arcavi|Drijvers|Stacey|2016|p=[https://books.google.com/books?id=N2R9DAAAQBAJ&pg=PA2 2]}} | {{harvnb|Benson|2003|pp=[https://books.google.com/books?id=nNbnCwAAQBAJ&pg=PA111 111–112]}} }}</ref> is the oldest and most basic form of algebra. It is a generalization of [[arithmetic]] that relies on [[Variable (mathematics)|variables]] and examines how mathematical [[Statement (logic)|statements]] may be transformed.<ref name="auto4">{{multiref | {{harvnb|Maddocks|2008|p=129}} | {{harvnb|Berggren|2015|loc=Lead section}} | {{harvnb|Pratt|2022|loc=§ 1. Elementary Algebra}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ 1. Historical Survey}} }}</ref>
An important class of problems in algebra is [[factorization]] of polynomials, that is, expressing a given polynomial as a product of other polynomials. The example polynomial above can be factored as <math>(x-1)(x+3)\,\!.</math> A related class of problems is finding algebraic expressions for the [[root (mathematics)|root]]s of a polynomial in a single variable.


Arithmetic is the study of numerical operations and investigates how numbers are combined and transformed using the arithmetic operations of [[addition]], [[subtraction]], [[multiplication]], [[Division (mathematics)|division]], [[exponentiation]], extraction of [[nth root|roots]], and [[logarithm]]. For example, the operation of addition combines two numbers, called the addends, into a third number, called the sum, as in {{nowrap|<math>2 + 5 = 7</math>.<ref name="auto1"/>}}
== Abstract algebra ==
{{main|Abstract algebra}} {{see also|Algebraic structure}}


Elementary algebra relies on the same operations while allowing variables in addition to regular numbers. Variables are [[symbol]]s for unspecified or unknown quantities. They make it possible to state relationships for which one does not know the exact values and to express general laws that are true, independent of which numbers are used. For example, the [[equation]] <math>2 \times 3 = 3 \times 2</math> belongs to arithmetic and expresses an equality only for these specific numbers. By replacing the numbers with variables, it is possible to express a general law that applies to any possible combination of numbers, like the [[Commutative property|commutative property of multiplication]], which is expressed in the equation {{nowrap|<math>a \times b = b \times a</math>.<ref name="auto4"/>}}
'''Abstract algebra''' extends the familiar concepts found in elementary algebra and [[arithmetic]] of [[number]]s to more general concepts.


[[Algebraic expression]]s are formed by using arithmetic operations to combine variables and numbers. By convention, the lowercase letters <math>x</math>, <math>y</math>, and <math>z</math> represent variables. In some cases, subscripts are added to distinguish variables, as in <math>x_1</math>, <math>x_2</math>, and <math>x_3</math>. The lowercase letters <math>a</math>, <math>b</math>, and <math>c</math> are usually used for [[Constant (mathematics)|constants]] and [[coefficient]]s.{{efn|Constants represent fixed magnitudes that, unlike variables, cannot change.<ref>{{harvnb|Sobolev|2015}}</ref>}} The expression <math>5x + 3</math> is an algebraic expression created by multiplying the number 5 with the variable <math>x</math> and adding the number 3 to the result. Other examples of algebraic expressions are <math>32xyz</math> and {{nowrap|<math>64x_1^2 + 7x_2 - c</math>.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=129–130}} | {{harvnb|Young|2010|p=[https://books.google.com/books?id=9HRLAn326zEC&pg=RA1-PA999 999]}} | {{harvnb|Majewski|2004|p=347}} | {{harvnb|Pratt|2022|loc=§ 1. Elementary Algebra}} | {{harvnb|Sorell|2000|p=[https://books.google.com/books?id=EksSDAAAQBAJ&pg=PA19 19]}} }}</ref>}}
'''[[Set]]s''': Rather than just considering the different types of [[number]]s, abstract algebra deals with the more general concept of ''sets'': a collection of all objects (called [[Element (mathematics)|elements]]) selected by property, specific for the set. All collections of the familiar types of numbers are sets. Other examples of sets include the set of all two-by-two [[Matrix (mathematics)|matrices]], the set of all second-degree [[polynomials]] (''ax''<sup>2</sup> + ''bx'' + ''c''), the set of all two dimensional [[vector (spatial)|vectors]] in the plane, and the various [[finite groups]] such as the [[cyclic group]]s which are the group of integers [[modular arithmetic|modulo]] ''n''. [[Set theory]] is a branch of [[logic]] and not technically a branch of algebra.


Some algebraic expressions take the form of statements that relate two expressions to one another. An equation is a statement formed by comparing two expressions, saying that they are equal. This can be expressed using the [[equals sign]] (<math>=</math>), as in {{nowrap|<math>5x^2 + 6x = 3y + 4</math>.}} [[Inequation]]s involve a different type of comparison, saying that the two sides are different. This can be expressed using symbols such as the [[less-than sign]] (<math><</math>), the [[greater-than sign]] (<math>></math>), and the inequality sign (<math>\neq</math>). Unlike other expressions, statements can be true or false and their truth value usually depends on the values of the variables. For example, the statement <math>x^2 = 4</math> is true if <math>x</math> is either 2 or &minus;2 and false otherwise.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=129–130}} | {{harvnb|Tsokos|Wooten|2015|p=[https://books.google.com/books?id=zu7HBQAAQBAJ&pg=PA451 451]}} | {{harvnb|Mishra|2016|p=1.2}} }}</ref> Equations with variables can be divided into identity equations and conditional equations. Identity equations are true for all values that can be assigned to the variables, such as the equation {{nowrap|<math>2x + 5x = 7x</math>.}} Conditional equations are only true for some values. For example, the equation <math>x + 4 = 9</math> is only true if <math>x</math> is 5.<ref>{{multiref | {{harvnb|Musser|Peterson|Burger|2013|p=16}} | {{harvnb|Goodman|2001|p=[https://books.google.com/books?id=TvY7DQAAQBAJ&pg=PA5 5]}} | {{harvnb|Williams|2022}} }}</ref>
'''[[Binary operation]]s''': The notion of [[addition]] (+) is abstracted to give a ''binary operation'', * say. The notion of binary operation is meaningless without the set on which the operation is defined. For two elements ''a'' and ''b'' in a set ''S'' ''a''*''b'' gives another element in the set; this condition is called [[Closure (mathematics)|closure]]. [[Addition]] (+), [[subtraction]] (-), [[multiplication]] (×), and [[Division (mathematics)|division]] (÷) can be binary operations when defined on different sets, as is addition and multiplication of matrices, vectors, and polynomials.


The main goal of elementary algebra is to determine the values for which a statement is true. This can be achieved by transforming and manipulating statements according to certain rules. A key principle guiding this process is that whatever operation is applied to one side of an equation also needs to be done to the other side. For example, if one subtracts 5 from the left side of an equation one also needs to subtract 5 from the right side to balance both sides. The goal of these steps is usually to isolate the variable one is interested in on one side, a process known as [[Equation solving|solving the equation]] for that variable. For example, the equation <math>x - 7 = 4</math> can be solved for <math>x</math> by adding 7 to both sides, which isolates <math>x</math> on the left side and results in the equation {{nowrap|<math>x = 11</math>.<ref>{{multiref | {{harvnb|Maddocks|2008|p=130}} | {{harvnb|McKeague|1986|pp=[https://books.google.com/books?id=sq7iBQAAQBAJ&pg=PA51 51–54]}} | {{harvnb|Pratt|2022|loc=§ 1. Elementary Algebra}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ 1. Historical Survey}} }}</ref>}}
'''[[Identity element]]s''': The numbers zero and one are abstracted to give the notion of an ''identity element'' for an operation. Zero is the identity element for addition and one is the identity element for multiplication. For a general binary operator * the identity element ''e'' must satisfy ''a'' * ''e'' = ''a'' and ''e'' * ''a'' = ''a''. This holds for addition as ''a'' + 0 = ''a'' and 0 + ''a'' = ''a'' and multiplication ''a'' &times; 1 = ''a'' and 1 &times; ''a'' = ''a''. However, if we take the positive natural numbers and addition, there is no identity element.


There are many other techniques used to solve equations. Simplification is employed to replace a complicated expression with an equivalent simpler one. For example, the expression <math>7x - 3x</math> can be replaced with the expression <math>4x</math> since <math>7x - 3x = (7-3)x = 4x</math> by the distributive property.<ref>{{multiref | {{harvnb|Tan|Steeb|Hardy|2012|p=[https://books.google.com/books?id=UDb0BwAAQBAJ&pg=PA306 306]}} | {{harvnb|Lamagna|2019|p=[https://books.google.com/books?id=8PSDDwAAQBAJ&pg=PA150 150]}} }}</ref> [[Factorization]] is used to rewrite an expression as a product of several factors. This technique is commonly used to determine the values of a [[polynomial]]{{efn|A polynomial is an expression consisting of one or more terms that are added or subtracted from each other. Each term is either a constant, a variable, or a product of a constant and variables. Each variable can be raised to a positive-integer power. Examples are <math>3x^2 - 7</math> and {{nowrap|<math>5x^3y + 4yz</math>.<ref>{{harvnb|Markushevich|2015}}</ref>}}}} that [[Zero of a function|evaluate to zero]]. For example, the polynomial <math>x^2 - 3x - 10</math> can be factorized as {{nowrap|<math>(x + 2)(x - 5)</math>.}} The polynomial as a whole is zero if and only if one of its factors is zero, i.e., if <math>x</math> is either &minus;2 or 5.<ref>{{multiref | {{harvnb|Lukas|2022|pp=[https://books.google.com/books?id=1-dvEAAAQBAJ&pg=PA47 47–49]}} | {{harvnb|Berggren|2015|loc=§ Algebraic Expressions, § Solving Algebraic Equations}} }}</ref> For statements with several variables, [[Substitution (logic)#Algebra|substitution]] is a common technique to replace one variable with an equivalent expression that does not use this variable. For example, if one knows that <math>y = 3x</math> then one can simplify the expression <math>7xy</math> to arrive at {{nowrap|<math>21x^2</math>.}} In a similar way, if one knows the value of one variable one may be able to use it to determine the value of other variables.<ref>{{multiref | {{harvnb|Berggren|2015|loc=§ Solving Systems of Algebraic Equations}} | {{harvnb|McKeague|2014|p=[https://books.google.com/books?id=nI7iBQAAQBAJ&pg=PA386 386]}} | {{harvnb|McKeague|1986|p=[https://books.google.com/books?id=sq7iBQAAQBAJ&pg=PA148 148]}} }}</ref>
'''[[Inverse elements]]''': The negative numbers give rise to the concept of ''inverse elements''. For addition, the inverse of ''a'' is ''-a'', and for multiplication the inverse is 1/''a''. A general inverse element ''a''<sup>-1</sup> must satisfy the property that ''a'' * ''a''<sup>-1</sup> = ''e'' and ''a''<sup>-1</sup> * ''a'' = ''e''.


[[File:Graph (y = 0.5x - 1).svg|thumb|class=skin-invert-image|alt=Graph of equation "y = 0.5x - 1"|Algebraic equations can be used to describe geometric figures. All values for <math>x</math> and <math>y</math> that solve the equation are interpreted as points. They are drawn as a red, upward-sloping line in the graph above.]]
'''[[Associativity]]''': Addition of integers has a property called associativity. That is, the grouping of the numbers to be added does not affect the sum. For example: (2+3)+4=2+(3+4). In general, this becomes (''a'' * ''b'') * ''c'' = ''a'' * (''b'' * ''c''). This property is shared by most binary operations, but not subtraction or division or [[octonion multiplication]].


Algebraic equations can be interpreted [[Geometry|geometrically]] to describe spatial figures in the form of a [[Graph of a function|graph]]. To do so, the different variables in the equation are understood as [[Cartesian coordinate system|coordinates]] and the values that solve the equation are interpreted as points of a graph. For example, if <math>x</math> is set to zero in the equation <math>y=0.5x - 1</math>, then <math>y</math> must be −1 for the equation to be true. This means that the <math>(x, y)</math>-pair <math>(0, -1)</math> is part of the graph of the equation. The <math>(x, y)</math>-pair {{nowrap|<math>(0, 7)</math>,}} by contrast, does not solve the equation and is therefore not part of the graph. The graph encompasses the totality of <math>(x, y)</math>-pairs that solve the equation.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=130–131}} | {{harvnb|Rohde|Jain|Poddar|Ghosh|2012|p=[https://books.google.com/books?id=vk2XbZpsBOwC&pg=PT89 89]}} | {{harvnb|Walz|2016|loc=[https://www.spektrum.de/lexikon/mathematik/algebra/12062 Algebra]}}}}</ref>
'''[[Commutative operation|Commutativity]]''': Addition of integers also has a property called commutativity. That is, the order of the numbers to be added does not affect the sum. For example: 2+3=3+2. In general, this becomes ''a'' * ''b'' = ''b'' * ''a''. Only some binary operations have this property. It holds for the integers with addition and multiplication, but it does not hold for [[matrix multiplication]] or [[Quaternion#Quaternion products|quaternion multiplication]] .


=== Linear algebra ===
=== Groups &ndash; structures of a set with a single binary operation ===
{{main|Linear algebra}}
{{main|Group (mathematics)}} {{see also|Group theory|Examples of groups}}


Linear algebra employs the methods of elementary algebra to study [[System of linear equations|systems of linear equations]].<ref>{{multiref | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Barrera-Mora|2023|pp=[https://books.google.com/books?id=Xmu8EAAAQBAJ&pg=PR9 ix, 1–2], }} }}</ref>{{efn|Another approach defines linear algebra as the study of [[linear map]]s between [[Dimension (vector space)|finite-dimensional]] vector spaces. A linear map is a function that transforms vectors from one [[vector space]] to another while preserving the operations of [[vector addition]] and [[scalar multiplication]]. Linear maps can be used to represent, analyze, and solve systems of linear equations.<ref>{{multiref | {{harvnb|Valenza|2012|p=[https://books.google.com/books?id=7x8MCAAAQBAJ&pg=PR7 vii]}} | {{harvnb|Chahal|2018|loc=[https://books.google.com/books?id=BGR8DwAAQBAJ&pg=PT10 § 1.1 What is Linear Algebra?]}} | {{harvnb|Solomon|2014|pp=[https://books.google.com/books?id=BpvSBQAAQBAJ&pg=PA57 57–58, 61–62]}} | {{harvnb|Ricardo|2009|p=[https://books.google.com/books?id=s7bMBQAAQBAJ&pg=PA389 389]}} }}</ref>}} An [[Linear equation|equation is linear]] if it can be expressed in the form <math>a_1x_1 + a_2x_2 + ... + a_nx_n = b</math> where <math>a_1</math>, <math>a_2</math>, ..., <math>a_n</math> and <math>b</math> are constants. This means that no variables are multiplied with each other and no variables are raised to a power greater than one. For example, the equations <math>x_1 - 7x_2 + 3x_3 = 0</math> and <math>0.25x - y = 4</math> are linear while the equations <math>x^2=y</math> and <math>3x_1x_2 + 15 = 0</math> are [[nonlinear system|non-linear]]. Several equations form a system of equations if they all rely on the same set of variables.<ref>{{multiref | {{harvnb|Anton|Rorres|2013|pp=2–3}} | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Voitsekhovskii|2011}} }}</ref>
Combining the above concepts gives one of the most important structures in mathematics: a '''[[group (mathematics)|group]]'''. A group is a combination of a set ''S'' and a single [[binary operation]] '*', defined in any way you choose, but with the following properties:


Systems of linear equations are often expressed through [[Matrix (mathematics)|matrices]]{{efn|A matrix is a table of numbers,<ref>{{multiref | {{harvnb|Saikia|2008|p=[https://books.google.com/books?id=KhM7BAAAQBAJ&pg=PA1 1]}} | {{harvnb|Lal|2017|p=[https://books.google.com/books?id=FwPNDgAAQBAJ&pg=PA31 31]}} }}</ref> such as <math display="block">\begin{bmatrix}3 & -7 & 19 \\ 0.3 & 7 & -4 \end{bmatrix}.</math>}} and [[Vector (mathematics and physics)|vectors]]{{efn|A vector is an array of numbers or a matrix with only one column,<ref>{{harvnb|Mirakhor|Krichene|2014|p=[https://books.google.com/books?id=G6XNAwAAQBAJ&pg=PT107 107]}}</ref> such as <math display="block">\begin{bmatrix} 2.1 \\ 0 \\ -1 \end{bmatrix}.</math>}} to represent the whole system in a single equation. This can be done by moving the variables to the left side of each equation and moving the constant terms to the right side. The system is then expressed by formulating a matrix that contains all the coefficients of the equations and [[Matrix multiplication|multiplying]] it with the [[column vector]] made up of the variables.<ref>{{multiref | {{harvnb|Barrera-Mora|2023|pp=[https://books.google.com/books?id=Xmu8EAAAQBAJ&pg=PR9 ix, 1, 12–13]}} | {{harvnb|Young|2010|pp=[https://books.google.com/books?id=9HRLAn326zEC&pg=PA726 726–727]}} | {{harvnb|Anton|Rorres|2013|pp=32–34}} }}</ref> For example, the system of equations
* An identity element ''e'' exists, such that for every member ''a'' of ''S'', ''e'' * ''a'' and ''a'' * ''e'' are both identical to ''a''.
<math display="block"> \begin{align}
* Every element has an inverse: for every member ''a'' of ''S'', there exists a member ''a''<sup>-1</sup> such that ''a'' * ''a''<sup>-1</sup> and ''a''<sup>-1</sup> * ''a'' are both identical to the identity element.
9x_1 + 3x_2 - 13x_3 &= 0 \\
* The operation is associative: if ''a'', ''b'' and ''c'' are members of ''S'', then (''a'' * ''b'') * ''c'' is identical to ''a'' * (''b'' * ''c'').
2.3x_1 + 7x_3 &= 9 \\
-5x_1 - 17x_2 &= -3
\end{align}
</math>
can be written as
<math display="block">\begin{bmatrix}9 & 3 & -13 \\ 2.3 & 0 & 7 \\ -5 & -17 & 0 \end{bmatrix} \begin{bmatrix}x_1 \\ x_2 \\ x_3 \end{bmatrix} = \begin{bmatrix}0 \\ 9 \\ -3 \end{bmatrix}</math>


Like elementary algebra, linear algebra is interested in manipulating and transforming equations to solve them. It goes beyond elementary algebra by dealing with several equations at once and looking for the values for which all equations are true at the same time. For example, if the system is made of the two equations <math>3x_1 - x_2 = 0</math> and <math>x_1 + x_2 = 8</math> then using the values 1 and 3 for <math>x_1</math> and <math>x_2</math> does not solve the system of equations because it only solves the first but not the second equation.<ref>{{multiref | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Andrilli|Hecker|2022|pp=[https://books.google.com/books?id=WtpVEAAAQBAJ&pg=PA57 57–58]}} }}</ref>
If a group is also [[commutativity|commutative]] - that is, for any two members ''a'' and ''b'' of ''S'', ''a'' * ''b'' is identical to ''b'' * ''a'' – then the group is said to be [[Abelian group|Abelian]].


Two central questions in linear algebra are whether a system of equations has any solutions and, if so, whether it has a unique solution. A system of equations has no solutions if it is [[Consistent and inconsistent equations|inconsistent]], meaning that two or more equations contradict each other. For example, the equations <math>x_1 - 3x_2 = 0</math> and <math>x_1 - 3x_2 = 7</math> contradict each other since no values of <math>x_1</math> and <math>x_2</math> exist that solve both equations at the same time. Only consistent systems of equations have solutions.<ref>{{multiref | {{harvnb|Anton|Rorres|2013|pp=3–7}} | {{harvnb|Mortensen|2013|pp=[https://books.google.com/books?id=KYDrCAAAQBAJ&pg=PA73 73–74]}} | {{harvnb|Young|2023|pp=[https://books.google.com/books?id=pMSZEAAAQBAJ&pg=PA714 714–715]}} }}</ref>
For example, the set of integers under the operation of addition is a group. In this group, the identity element is 0 and the inverse of any element ''a'' is its negation, -''a''. The associativity requirement is met, because for any integers ''a'', ''b'' and ''c'', (''a'' + ''b'') + ''c'' = ''a'' + (''b'' + ''c'')


Whether a consistent system of equations has a unique solution depends on the number of variables and [[Independent equation|independent equations]]. Several equations are independent of each other if they do not provide the same information and cannot be derived from each other. A unique solution exists if the number of variables is the same as the number of independent equations. [[Underdetermined system]]s, by contrast, have more variables than independent equations and have an infinite number of solutions if they are consistent.<ref>{{multiref | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Harrison|Waldron|2011|p=[https://books.google.com/books?id=_sisAgAAQBAJ&pg=PT464 464]}} | {{harvnb|Anton|2013|p=[https://books.google.com/books?id=neYGCwAAQBAJ&pg=PA255 255]}} }}</ref>
The nonzero [[rational number]]s form a group under multiplication. Here, the identity element is 1, since 1 &times; ''a'' = ''a'' &times; 1 = ''a'' for any rational number ''a''. The inverse of ''a'' is 1/''a'', since ''a'' &times; 1/''a'' = 1.


[[File:Linear Function Graph.svg|thumb|alt=Graph of two linear equations|Linear equations with two variables can be interpreted geometrically as lines. The solution of a system of linear equations is where the lines intersect.]]
The integers under the multiplication operation, however, do not form a group. This is because, in general, the multiplicative inverse of an integer is not an integer. For example, 4 is an integer, but its multiplicative inverse is 1/4, which is not an integer.


Many techniques employed in elementary algebra to solve equations are also applied in linear algebra. The substitution method starts with one equation and isolates one variable in it. It proceeds to the next equation and replaces the isolated variable with the found expression, thereby reducing the number of unknown variables by one. It applies the same process again to this and the remaining equations until the values of all variables are determined.<ref>{{multiref | {{harvnb|Young|2010|pp=[https://books.google.com/books?id=9HRLAn326zEC&pg=PA697 697–698]}} | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Sullivan|2010|pp=[https://books.google.com/books?id=6NKaDwAAQBAJ&pg=PA53 53–54]}} }}</ref> The elimination method creates a new equation by adding one equation to another equation. This way, it is possible to eliminate one variable that appears in both equations. For a system that contains the equations <math>-x + 7y = 3</math> and {{nowrap|<math>2x - 7y = 10</math>,}} it is possible to eliminate <math>y</math> by adding the first to the second equation, thereby revealing that <math>x</math> is 13. In some cases, the equation has to be multiplied by a constant before adding it to another equation.<ref>{{multiref | {{harvnb|Anton|Rorres|2013|pp=7–8}} | {{harvnb|Sullivan|2010|pp=[https://books.google.com/books?id=6NKaDwAAQBAJ&pg=PA55 55–56]}} | {{harvnb|Atanasiu|Mikusinski|2019|p=[https://books.google.com/books?id=VbySDwAAQBAJ&pg=PA75 75]}}}}</ref> Many advanced techniques implement algorithms based on matrix calculations, such as [[Cramer's rule]], the [[Gauss–Jordan elimination]], and [[LU decomposition]].<ref>{{multiref | {{harvnb|Maddocks|2008|p=131}} | {{harvnb|Anton|Rorres|2013|pp=7–8, 11, 491}} }}</ref>
The theory of groups is studied in [[group theory]]. A major result in this theory is the [[classification of finite simple groups]], mostly published between about 1955 and 1983, which is thought to classify all of the [[finite set|finite]] [[simple group]]s into roughly 30 basic types.


Systems of equations can be interpreted as geometric figures. For systems with two variables, each equation represents a [[Line (geometry)|line]] in [[two-dimensional space]]. The point where the two lines intersect is the solution of the full system because this is the only point that solves both the first and the second equation. For inconsistent systems, the two lines run parallel, meaning that there is no solution since they never intersect. If two equations are not independent then they describe the same line, meaning that every solution of one equation is also a solution of the other equation. These relations make it possible to seek solutions graphically by plotting the equations and determining where they intersect.<ref>{{multiref | {{harvnb|Anton|Rorres|2013|pp=3–5}} | {{harvnb|Young|2010|pp=[https://books.google.com/books?id=9HRLAn326zEC&pg=PA696 696–697]}} | {{harvnb|Sneyd|Fewster|McGillivray|2022|p=[https://books.google.com/books?id=zqd3EAAAQBAJ&pg=PA211 211]}} }}</ref> The same principles also apply to systems of equations with more variables, with the difference being that the equations do not describe lines but higher dimensional figures. For instance, equations with three variables correspond to [[Plane (mathematics)|planes]] in [[three-dimensional space]], and the points where all planes intersect solve the system of equations.<ref>{{multiref | {{harvnb|Anton|Rorres|2013|pp=3–5}} | {{harvnb|Young|2010|p=[https://books.google.com/books?id=9HRLAn326zEC&pg=PA713 713]}} | {{harvnb|Sneyd|Fewster|McGillivray|2022|p=[https://books.google.com/books?id=zqd3EAAAQBAJ&pg=PA211 211]}} }}</ref>
{| class="wikitable"
|-
| colspan=11|Examples
|-
!Set:
| colspan=2|[[Natural numbers]] <math>\mathbb{N}</math>
| colspan=2|[[Integers]] <math>\mathbb{Z}</math>
| colspan=4|[[Rational numbers]] <math>\mathbb{Q}</math> (also [[Real numbers|real]] <math>\mathbb{R}</math> and [[Complex numbers|complex]] <math>\mathbb{C}</math> numbers)
| colspan=2|Integers mod 3: {0,1,2}
|-
!Operation
| +
| × (w/o zero)
| +
| × (w/o zero)
| +
| −
| × (w/o zero)
| ÷ (w/o zero)
| +
| × (w/o zero)
|-
!Closed
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
| Yes
|-
| Identity
| 0
| 1
| 0
| 1
| 0
| NA
| 1
| NA
| 0
| 1
|-
| Inverse
| NA
| NA
| -a
| NA
| -a
| NA
| <math>\begin{matrix} \frac{1}{a} \end{matrix}</math>
| NA
| 0,2,1, respectively
| NA, 1, 2, respectively
|-
| Associative
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| Yes
| No
| Yes
| Yes
|-
| Commutative
| Yes
| Yes
| Yes
| Yes
| Yes
| No
| Yes
| No
| Yes
| Yes
|-
| Structure
| [[monoid]]
| [[monoid]]
| [[Abelian group]]
| [[monoid]]
| [[Abelian group]]
| [[quasigroup]]
| [[Abelian group]]
| [[quasigroup]]
| [[Abelian group]]
| [[Abelian group]] (<math>\mathbb{Z}_2</math>)
|}


=== Abstract algebra ===
[[Semigroup]]s, [[quasigroup]]s, and [[monoid]]s are structures similar to groups, but more general. They comprise a set and a closed binary operation, but do not necessarily satisfy the other conditions. A [[semigroup]] has an ''associative'' binary operation, but might not have an identity element. A [[monoid]] is a semigroup which does have an identity but might not have an inverse for every element. A [[quasigroup]] satisfies a requirement that any element can be turned into any other by a unique pre- or post-operation; however the binary operation might not be associative.
{{main|Abstract algebra}}


Abstract algebra, also called modern algebra,<ref>{{multiref | {{harvnb|Gilbert|Nicholson|2004|p=[https://books.google.com/books?id=paINAXYHN8kC&pg=PA1 1]}} | {{harvnb|Dominich|2008|p=[https://books.google.com/books?id=uEedNKV3nlUC&pg=PA19 19]}} }}</ref> studies different types of [[algebraic structures]]. An algebraic structure is a framework for understanding [[Operation (mathematics)|operations]] on [[mathematical object]]s, like the addition of numbers. While elementary algebra and linear algebra work within the confines of particular algebraic structures, abstract algebra takes a more general approach that compares how algebraic structures differ from each other and what types of algebraic structures there are, such as [[Group (mathematics)|groups]], [[Ring (mathematics)|rings]], and [[Field (mathematics)|fields]].<ref>{{multiref | {{harvnb|Maddocks|2008|pp=131–132}} | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} | {{harvnb|Gilbert|Nicholson|2004|pp=[https://books.google.com/books?id=paINAXYHN8kC&pg=PA1 1–3]}} | {{harvnb|Dominich|2008|p=[https://books.google.com/books?id=uEedNKV3nlUC&pg=PA19 19]}} }}</ref> The key difference between these types of algebraic structures lies in the number of operations they use and the laws they obey.<ref name="auto9"/>
All groups are monoids, and all monoids are semigroups.


[[File:Binary operations as black box.svg|thumb|class=skin-invert-image|alt=Diagram of binary operation|Many algebraic structures rely on binary operations, which take two objects as their input and combine them into a single object as output, like addition and multiplication do.]]
=== Rings and fields&mdash;structures of a set with two particular binary operations, (+) and (×) ===
{{main|ring (mathematics)|field (mathematics)}} {{see also|Ring theory|Glossary of ring theory|Field theory (mathematics)|glossary of field theory}}


On a formal level, an algebraic structure is a [[Set (mathematics)|set]]{{efn|A set is an unordered collection of distinct elements, such as numbers, vectors, or other sets. [[Set theory]] describes the laws and properties of sets.<ref>{{multiref | {{harvnb|Tanton|2005|p=460}} | {{harvnb|Murthy|2012|p=[https://books.google.com/books?id=CBc8BAAAQBAJ&pg=PA3 1.3]}} }}</ref>}} of mathematical objects, called the underlying set, together with one or several operations.{{efn|According to some definitions, algebraic structures include a distinguished element as an additional component, such as the identity element in the case of multiplication.<ref name="auto5">{{harvnb|Ovchinnikov|2015|p=[https://books.google.com/books?id=UMbXBgAAQBAJ&pg=PA27 27]}}</ref>}} Abstract algebra is primarily interested in [[binary operation]]s,{{efn|Some of the algebraic structures studied by abstract algebra include [[unary operation]]s in addition to binary operations. For example, [[normed vector space]]s have a [[Norm (mathematics)|norm]], which is a unary operation often used to associate a vector with its length.<ref>{{harvnb|Grillet|2007|p=[https://books.google.com/books?id=LJtyhu8-xYwC&pg=PA247 247]}}</ref>}} which take any two objects from the underlying set as inputs and map them to another object from this set as output.<ref>{{multiref | {{harvnb|Whitelaw|1995|p=[https://books.google.com/books?id=f2hyf0QoB_0C&pg=PA61 61]}} | {{harvnb|Nicholson|2012|p=[https://books.google.com/books?id=w-GaLpapRcEC&pg=PA70 70]}} | {{harvnb|Fiche|Hebuterne|2013|p=[https://books.google.com/books?id=TqkckiuuXg8C&pg=PT326 326]}} | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} }}</ref> For example, the algebraic structure <math>\langle \N, + \rangle</math> has the [[natural numbers]] (<math>\N</math>) as the underlying set and addition (<math>+</math>) as its binary operation.<ref name="auto5"/> The underlying set can contain mathematical objects other than numbers and the operations are not restricted to regular arithmetic operations.<ref>{{multiref | {{harvnb|Maddocks|2008|pp=131–132}} | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} }}</ref> For instance, the underlying set of the [[symmetry group]] of a geometric object is made up of [[geometric transformation]]s, such as [[rotation]]s, under which the object remains [[Invariant (mathematics)|unchanged]]. Its binary operation is [[function composition]], which takes two transformations as input and has the transformation resulting from applying the first transformation followed by the second as its output.<ref>{{multiref | {{harvnb|Olver|1999|pp=[https://books.google.com/books?id=1GlHYhNRAqEC&pg=PA55 55–56]}} | {{harvnb|Abas|Salman|1994|pp=[https://books.google.com/books?id=5snsCgAAQBAJ&pg=PA58 58–59]}} | {{harvnb|Häberle|2009|p=[https://books.google.com/books?id=McvSa-cFZCMC&pg=PA640 640]}} }}</ref>
Groups just have one binary operation. To fully explain the behaviour of the different types of numbers, structures with two operators need to be studied. The most important of these are [[Ring (mathematics)|rings]], and [[Field (mathematics)|fields]].


Abstract algebra classifies algebraic structures based on the laws or [[axiom]]s that its operations obey and the number of operations it uses. One of the most basic types is a group, which has one operation and requires that this operation is [[Associative property|associative]] and has an [[identity element]] and [[Inverse element|inverse elements]]. An operation is associative if the order of several applications does not matter, i.e., if {{nowrap|<math>(a \circ b) \circ c</math>{{efn|The symbols <math>\circ</math> and <math>\star</math> are used in this article to represent any operation that may or may not resemble arithmetic operations.<ref>{{harvnb|Gilbert|Nicholson|2004|p=[https://books.google.com/books?id=paINAXYHN8kC&pg=PA4 4]}}</ref>}}}} is the same as <math>a \circ (b \circ c)</math> for all elements. An operation has an identity element or a neutral element if one element ''e'' exists that does not change the value of any other element, i.e., if {{nowrap|<math>a \circ e = e \circ a = a</math>.}} An operation has inverse elements if for any element <math>a</math> there exists a reciprocal element <math>a^{-1}</math> that undoes <math>a</math>. If an element operates on its inverse then the result is the neutral element ''e'', expressed formally as {{nowrap|<math>a \circ a^{-1} = a^{-1} \circ a = e</math>.}} Every algebraic structure that fulfills these requirements is a group.<ref>{{multiref | {{harvnb|Kargapolov|Merzlyakov|2016|loc=§ Definition}} | {{harvnb|Khattar|Agrawal|2023|pp=[https://books.google.com/books?id=7-nIEAAAQBAJ&pg=PA4 4–6]}} | {{harvnb|Maddocks|2008|pp=131–132}} | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} | {{harvnb|Neri|2019|p=[https://books.google.com/books?id=NMOlDwAAQBAJ&pg=PA258 258]}} }}</ref> For example, <math>\langle \Z, + \rangle</math> is a group formed by the set of [[integers]] together with the operation of addition. The neutral element is 0 and the inverse element of any number <math>a</math> is {{nowrap|<math>-a</math>.<ref>{{multiref | {{harvnb|Khattar|Agrawal|2023|pp=[https://books.google.com/books?id=7-nIEAAAQBAJ&pg=PA6 6–7]}} | {{harvnb|Maddocks|2008|pp=131–132}} | {{harvnb|Adhikari|Adhikari|2013|p=[https://books.google.com/books?id=lBO7BAAAQBAJ&pg=PA72 72]}}}}</ref>}} The natural numbers with addition, by contrast, do not form a group since they contain only positive integers and therefore lack inverse elements.<ref>{{multiref | {{harvnb|McWeeny|2002|p=[https://books.google.com/books?id=x3fjIXY93TsC&pg=PA6 6]}} | {{harvnb|Kramer|Pippich|2017|p=[https://books.google.com/books?id=nvM-DwAAQBAJ&pg=PA49 49]}} }}</ref> [[Group theory]] is the subdiscipline of abstract algebra which studies groups.<ref>{{harvnb|Tanton|2005|p=242}}</ref>
'''[[Distributivity]]''' generalised the ''distributive law'' for numbers, and specifies the order in which the operators should be applied, (called the [[Order of operations|precedence]]). For the integers (''a'' + ''b'') &times; c = ''a''&times;''c''+ ''b''&times;''c'' and ''c'' &times; (''a'' + ''b'') = ''c''&times;''a'' + ''c''&times;''b'', and &times; is said to be ''distributive'' over +.


A ring is an algebraic structure with two operations (<math>\circ</math> and <math>\star</math>) that work similarly to addition and multiplication. All the requirements of groups also apply to the first operation: it is associative and has an identity element and inverse elements. Additionally, it is commutative, meaning that <math>a \circ b = b \circ a</math> is true for all elements. The axiom of [[Distributive Property|distributivity]] governs how the two operations interact with each other. It states that <math>a \star (b \circ c) = (a \star b) \circ (a \star c)</math> and {{nowrap|<math>(b \circ c) \star a = (b \star a) \circ (c \star a)</math>.<ref>{{multiref | {{harvnb|Weisstein|2003|p=2579}} | {{harvnb|Ivanova|2016}} | {{harvnb|Maxwell|2009|pp=[https://books.google.com/books?id=yD0irRUE_u4C&pg=PA73 73–74]}} | {{harvnb|Pratt|2022|loc=§ 2.3 Rings}} }}</ref>}} The [[ring of integers]] is the ring denoted by {{nowrap|<math>\langle \Z, +, \times \rangle</math>.<ref>{{harvnb|Smith|2015|p=[https://books.google.com/books?id=MXu9CgAAQBAJ&pg=PA161 161]}}</ref>{{efn|Some definitions additionally require that the second operation is associative.<ref>{{harvnb|Weisstein|2003|p=2579}}</ref>}}}} A ring becomes a field if both operations follow the axioms of associativity, commutativity, and distributivity and if both operations have an identity element and inverse elements.<ref>{{multiref | {{harvnb|Weisstein|2003|pp=1047, 2579}} | {{harvnb|Pratt|2022|loc=§ 2.4 Fields}} }}</ref>{{efn|For the second operation, there is usually one element, corresponding to 0, that does not require an inverse element.<ref>{{harvnb|Weisstein|2003|p=1047}}</ref>}} The ring of integers does not form a field because it lacks multiplicative inverses. For example, the multiplicative inverse of <math>7</math> is {{nowrap|<math>\tfrac{1}{7}</math>,}} which is not part of the integers. The [[rational numbers]], the [[real numbers]], and the [[complex numbers]] each form a field with the operations addition and multiplication.<ref>{{multiref | {{harvnb|Irving|2004|pp=77, 236}} | {{harvnb|Weisstein|2003|pp=1047, 2579}} | {{harvnb|Negro|2022|p=[https://books.google.com/books?id=MIdoEAAAQBAJ&pg=PA365 365]}} }}</ref>
A '''[[Ring (mathematics)|ring]]''' has two binary operations (+) and (×), with × distributive over +. Under the first operator (+) it forms an ''Abelian group''. Under the second operator (×) it is associative, but it does not need to have identity, or inverse, so division is not allowed. The additive (+) identity element is written as 0 and the additive inverse of ''a'' is written as &minus;''a''.


[[File:Magma to group4.svg|thumb|class=skin-invert-image|alt=Diagram of relations between some algebraic structures|Diagram of relations between some algebraic structures. For instance, its top right section shows that a [[Magma (algebra)|magma]] becomes a [[Semigroup|semigroup]] if its operation is associative.]]
The integers are an example of a ring. The integers have additional properties which make it an '''[[integral domain]]'''.


Besides groups, rings, and fields, there are many other algebraic structures studied by abstract algebra. They include [[Magma (algebra)|magmas]], [[Semigroup|semigroups]], [[Monoid|monoids]], [[Abelian group|abelian groups]], [[Commutative ring|commutative rings]], [[Module (mathematics)|modules]], [[Lattice (order)|lattices]], [[Vector space|vector spaces]], and [[Algebra over a field|algebras over a field]]. They differ from each other in regard to the types of objects they describe and the requirements that their operations fulfill. Many are related to each other in that a basic structure can be turned into a more advanced structure by adding additional requirements.<ref name="auto9">{{multiref | {{harvnb|Pratt|2022|loc=Lead section, § 2. Abstract Algebra}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=The Subject Matter of Algebra, Its Principal Branches and Its Connection with Other Branches of Mathematics.}} }}</ref> For example, a magma becomes a semigroup if its operation is associative.<ref>{{harvnb|Cooper|2011|p=[https://books.google.com/books?id=Fybzl6QB62gC&pg=PA60 60]}}</ref>
A '''[[Field (mathematics)|field]]''' is a ''ring'' with the additional property that all the elements excluding 0 form an ''Abelian group'' under ×. The multiplicative (×) identity is written as 1 and the multiplicative inverse of ''a'' is written as ''a''<sup>-1</sup>.


=== Universal algebra ===
The rational numbers, the real numbers and the complex numbers are all examples of fields.
{{main|Universal algebra}}


Universal algebra is the study of algebraic structures in general. As part of its general perspective, it is not concerned with the specific elements that make up the underlying sets and considers operations with more than two inputs, such as [[ternary operation]]s. It provides a framework for investigating what structural features different algebraic structures have in common.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 3. Universal Algebra}} | {{harvnb|Cohn|2012|p=[https://books.google.com/books?id=6tbuCAAAQBAJ&pg=PR13 xiii]}} }}</ref>{{efn|A slightly different approach understands universal algebra as the study of one type of algebraic structures known as universal algebras. Universal algebras are defined in a general manner to include most other algebraic structures. For example, groups and rings are special types of universal algebras.<ref>{{multiref | {{harvnb|Smirnov|2020}} | {{harvnb|Grätzer|2008|pp=7–8}} | {{harvnb|Bahturin|2013|p=[https://books.google.com/books?id=8RbvCAAAQBAJ&pg=PA346 346]}} }}</ref>}} One of those structural features concerns the [[Identity (mathematics)#Logic and universal algebra|identities]] that are true in different algebraic structures. In this context, an identity is a [[Universal quantification|universal]] equation or an equation that is true for all elements of the underlying set. For example, commutativity is a universal equation that states that <math>a \circ b</math> is identical to <math>b \circ a</math> for all elements.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 3.2 Equational Logic}} | {{harvnb|Mal’cev|1973|pp=210–211}} }}</ref> Two algebraic structures that share all their identities are said to belong to the same [[Variety (universal algebra)|variety]].<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 3. Universal Algebra}} | {{harvnb|Mal’cev|1973|pp=210–211}} }}</ref> For instance, the ring of integers and the [[Polynomial ring|ring of polynomials]] form part of the same variety because they have the same identities, like commutativity and associativity. The field of rational numbers, by contrast, does not belong to this variety since it has additional identities, such as the existence of multiplicative inverses.<ref>{{multiref | {{harvnb|Cox|Little|O'Shea|2015|p=[https://books.google.com/books?id=yL7yCAAAQBAJ&pg=PA268 268]}} | {{harvnb|Negro|2022|p=[https://books.google.com/books?id=MIdoEAAAQBAJ&pg=PA365 365]}} }}</ref>{{efn|Besides identities, universal algebra is also interested in structural features associated with [[quasi-identity|quasi-identities]]. A quasi-identity is an identity that only needs to be present under certain conditions.{{efn|The conditions take the form of a [[Horn clause]].<ref>{{harvnb|Mal’cev|1973|p=211}}</ref>}} It is a generalization of identity in the sense that every identity is a quasi-identity but not every quasi-identity is an identity. Algebraic structures that share all their quasi-identities have certain structural characteristics in common, which is expressed by stating that they belong to the same [[quasivariety]].<ref>{{multiref | {{harvnb|Mal’cev|1973|pp=210–211}} | {{harvnb|Pratt|2022|loc=§ 3. Universal Algebra}} | {{harvnb|Artamonov|2003|p=[https://books.google.com/books?id=sLDGY4Hk8V0C&pg=PA873 873]}} }}</ref>}}
== Objects called algebras ==


[[Homomorphism]]s are tools in universal algebra to examine structural features by comparing two algebraic structures.<ref>{{multiref | {{harvnb|Rowen|2006|p=[https://books.google.com/books?id=AhEPCgAAQBAJ&pg=PA12 12]}} | {{harvnb|Pratt|2022|loc=§ 3.3 Birkhoff’s Theorem}} | {{harvnb|Grätzer|2008|p=34}} }}</ref> A homomorphism is a function from the underlying set of one algebraic structure to the underlying set of another algebraic structure that preserves certain structural characteristics. If the two algebraic structures use binary operations and have the form <math>\langle A, \circ \rangle</math> and <math>\langle B, \star \rangle</math> then the function <math>h: A \to B</math> is a homomorphism if it fulfills the following requirement: {{nowrap|<math>h(x \circ y) = h(x) \star h(y)</math>.}} The existence of a homomorphism reveals that the operation <math>\star</math> in the second algebraic structure plays the same role as the operation <math>\circ</math> does in the first algebraic structure.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 3.3 Birkhoff’s Theorem}} | {{harvnb|Rowen|2006|p=[https://books.google.com/books?id=AhEPCgAAQBAJ&pg=PA12 12]}} | {{harvnb|Silvia|Robinson|1979|p=[https://books.google.com/books?id=Ecgfjh-MpU0C&pg=PA82 82]}} | {{harvnb|Adhikari|2016|pp=[https://books.google.com/books?id=MIAXDQAAQBAJ&pg=PA5 5–6]}} }}</ref> [[Isomorphisms]] are a special type of homomorphism that indicates a high degree of similarity between two algebraic structures. An isomorphism is a [[bijective]] homomorphism, meaning that it establishes a one-to-one relationship between the elements of the two algebraic structures. This implies that every element of the first algebraic structure is mapped to one unique element in the second structure without any unmapped elements in the second structure.<ref>{{multiref | {{harvnb|Neri|2019|pp=[https://books.google.com/books?id=NMOlDwAAQBAJ&pg=PA278 278–279]}} | {{harvnb|Ivanova|Smirnov|2012}} | {{harvnb|Deo|2018|p=[https://books.google.com/books?id=HjtRDwAAQBAJ&pg=PA295 295]}} | {{harvnb|Ono|2019|p=[https://books.google.com/books?id=SR2nDwAAQBAJ&pg=PA84 84]}}}}</ref>
The word '''''algebra''''' is also used for various [[algebraic structures]]:


[[File:Venn A subset B.svg|thumb|alt=Venn diagram of a set and its subset|[[Subalgebra]]s restrict their operations to a subset of the underlying set of the original algebraic structure.]]
* [[Algebra over a field]] or more generally [[Algebra (ring theory)|Algebra over a ring]]

* [[Algebra over a set]]
Another tool of comparison is the relation between an algebraic structure and its [[Subalgebra#Subalgebras in universal algebra|subalgebra]].<ref name="auto8">{{multiref | {{harvnb|Indurkhya|2013|pp=[https://books.google.com/books?id=foTrCAAAQBAJ&pg=PA217 217–218]}} | {{harvnb|Pratt|2022|loc=§ 3.3 Birkhoff’s Theorem}} | {{harvnb|Grätzer|2008|p=34}} }}</ref> The algebraic structure and its subalgebra use the same operations,{{efn|According to some definitions, it is also possible for a subalgebra to have fewer operations.<ref name="auto6">{{harvnb|Indurkhya|2013|pp=[https://books.google.com/books?id=foTrCAAAQBAJ&pg=PA217 217–218]}}</ref>}} which follow the same axioms. The only difference is that the underlying set of the subalgebra is a subset of the underlying set of the algebraic structure.{{efn|This means that all the elements of the first set are also elements of the second set but the second set may contain elements not found in the first set.<ref>{{harvnb|Efimov|2014}}</ref>}} All operations in the subalgebra are required to be [[Closure (mathematics)|closed]] in its underlying set, meaning that they only produce elements that belong to this set.<ref name="auto8"/> For example, the set of [[Parity (mathematics)|even integers]] together with addition is a subalgebra of the full set of integers together with addition. This is the case because the sum of two even numbers is again an even number. But the set of odd integers together with addition is not a subalgebra because it is not closed: adding two odd numbers produces an even number, which is not part of the chosen subset.<ref name="auto6"/>
* [[Boolean algebra (structure)|Boolean algebra]]
* [[F-algebra]] and [[F-coalgebra]] in [[category theory]]
* [[Sigma-algebra]]
* [[Monad (category theory)|T-Algebras of monads]].


== History ==
== History ==
{{Main|History of algebra}}
{{main|History of algebra|Timeline of algebra}}
{{See also|Timeline of algebra}}


[[File:Rhind Mathematical Papyrus.jpg|thumb|alt=Rhind Papyrus|The [[Rhind Mathematical Papyrus]] from [[ancient Egypt]], dated {{circa|1650 BCE}}, is one of the earliest documents discussing algebraic problems.]]
[[Image:Image-Al-Kitāb al-muḫtaṣar fī ḥisāb al-ğabr wa-l-muqābala.jpg|thumb|A page from [[:en:Muhammad ibn Musa al-Khwarizmi|Al-Khwārizmī]]'s ''[[The Compendious Book on Calculation by Completion and Balancing|al-Kitāb al-muḫtaṣar fī ḥisāb al-ğabr wa-l-muqābala]]'']]


The origin of algebra lies in attempts to solve mathematical problems involving arithmetic calculations and unknown quantities. These developments happened in the ancient period in [[Babylonia]], [[Ancient Egypt|Egypt]], [[Ancient Greece|Greece]], [[Ancient China|China]], and [[Ancient India|India]]. One of the earliest documents on algebraic problems is the [[Rhind Mathematical Papyrus]] from ancient Egypt, which was written around 1650&nbsp;BCE.{{efn|The exact date is disputed and some historians suggest a later date around 1550 BCE.<ref>{{multiref | {{harvnb|Corry|2024|loc=§ Problem Solving in Egypt and Babylon}} | {{harvnb|Brezinski|Meurant|Redivo-Zaglia|2022|p=[https://books.google.com/books?id=4IGhEAAAQBAJ&pg=PA34 34]}} }}</ref>}} It discusses solutions to [[linear equations]], as expressed in problems like "A quantity; its fourth is added to it. It becomes fifteen. What is the quantity?" Babylonian clay tablets from around the same time explain methods to solve linear and [[Quadratic equation|quadratic polynomial equations]], such as the method of [[completing the square]].<ref>{{multiref | {{harvnb|Tanton|2005|p=9}} | {{harvnb|Kvasz|2006|p=290}} | {{harvnb|Corry|2024|loc=§ Problem Solving in Egypt and Babylon}} }}</ref>
The origins of algebra can be traced to the ancient [[Babylonian mathematics|Babylonians]],<ref>Struik, Dirk J. (1987). ''A Concise History of Mathematics''. New York: Dover Publications.</ref> who developed an advanced [[arithmetic|arithmetical system]] with which they were able to do calculations in an algebraic fashion. With the use of this system they were able to apply formulas and calculate solutions for unknown values for a class of problems typically solved today by using [[linear equation]]s, [[quadratic equation]]s, and [[indeterminate equation|indeterminate linear equation]]s. By contrast, most [[Egyptian mathematics|Egyptians]] of this era, and most [[Indian mathematics|Indian]], [[Greek mathematics|Greek]] and [[Chinese mathematics|Chinese]] mathematicians in the [[1st millennium BC|first millennium BC]], usually solved such equations by [[geometry|geometric]] methods, such as those described in the ''[[Rhind Mathematical Papyrus]]'', ''[[Sulba Sutras]]'', [[Euclid's Elements|Euclid's ''Elements'']], and ''[[The Nine Chapters on the Mathematical Art]]''. The geometric work of the Greeks, typified in the ''Elements'', provided the framework for generalizing formulae beyond the solution of particular problems into more general systems of stating and solving equations.


Many of these insights found their way to the ancient Greeks. Starting in the 6th century BCE, their main interest was geometry rather than algebra, but they employed algebraic methods to solve geometric problems. For example, they studied geometric figures while taking their lengths and areas as unknown quantities to be determined, as exemplified in [[Pythagoras]]' formulation of the [[difference of two squares]] method and later in [[Euclid's Elements|Euclid's ''Elements'']].<ref>{{multiref | {{harvnb|Tanton|2005|p=9}} | {{harvnb|Kvasz|2006|p=290}} | {{harvnb|Corry|2024|loc=§ The Pythagoreans and Euclid}} }}</ref> In the 3rd century CE, [[Diophantus]] provided a detailed treatment of how to solve algebraic equations in a series of books called ''[[Arithmetica]]''. He was the first to experiment with symbolic notation to express polynomials.<ref>{{multiref | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Sialaros|2018|p=[https://books.google.com/books?id=2PZYDwAAQBAJ&pg=PT55 55]}} | {{harvnb|Musielak|2020|p=[https://books.google.com/books?id=iqHYDwAAQBAJ&pg=PA36 36]}} | {{harvnb|Corry|2024|loc=§ Diophantus}} }}</ref> In ancient China, ''[[The Nine Chapters on the Mathematical Art]]'', a book composed over the period spanning from the 10th century BCE to the 2nd century CE,<ref>{{harvnb|Burgin|2022|p=[https://books.google.com/books?id=rWF2EAAAQBAJ&pg=PA10 10]}}</ref> explored various techniques for solving algebraic equations, including the use of matrix-like constructs.<ref>{{harvnb|Higgins|2015|p=[https://books.google.com/books?id=QANiCgAAQBAJ&pg=PA89 89]}}</ref>
Later, the [[Indian mathematics|Indian mathematicians]] developed algebraic methods to a high degree of sophistication. Although Diophantus and the Babylonians used mostly special ad hoc methods to solve equations, [[Brahmagupta]] was the first to solve equations using general methods. He solved the linear indeterminate equations, quadratic equations, second order indeterminate equations and equations with multiple variable.


It is controversial to what extent these early developments should be considered part of algebra proper rather than precursors. They offered solutions to algebraic problems but did not conceive them in an abstract and general manner, focusing instead on specific cases and applications.<ref>{{multiref | {{harvnb|Kvasz|2006|pp=290–291}} | {{harvnb|Sialaros|2018|p=[https://books.google.com/books?id=2PZYDwAAQBAJ&pg=PT55 55]}} | {{harvnb|Boyer|Merzbach|2011|p=[https://books.google.com/books?id=bR9HAAAAQBAJ&pg=PA161 161]}} | {{harvnb|Derbyshire|2006|p=[https://books.google.com/books?id=mLqaAgAAQBAJ&pg=PT39 31]}} }}</ref> This changed with the Persian mathematician [[al-Khwarizmi]],{{efn|Some historians consider him the "father of algebra" while others reserve this title for Diophantus.<ref>{{multiref | {{harvnb|Boyer|Merzbach|2011|p=[https://books.google.com/books?id=bR9HAAAAQBAJ&pg=PA161 161]}} | {{harvnb|Derbyshire|2006|p=[https://books.google.com/books?id=mLqaAgAAQBAJ&pg=PA31 31]}} }}</ref> }} who published his ''[[The Compendious Book on Calculation by Completion and Balancing]]'' in 825 CE. It presents the first detailed treatment of general methods that can be used to manipulate linear and quadratic equations by "reducing" and "balancing" both sides.<ref>{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Kvasz|2006|pp=291–293}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} }}</ref> Other influential contributions to algebra came from the Arab mathematician [[Thābit ibn Qurra]] also in the 9th century and the Persian mathematician [[Omar Khayyam]] in the 11th and 12th centuries.<ref>{{multiref | {{harvnb|Waerden|2013|pp=3, 15–16, 24–25}} | {{harvnb|Jenkins|2010|p=[https://books.google.com/books?id=giEkCQAAQBAJ&pg=PA82 82]}} | {{harvnb|Pickover|2009|p=[https://books.google.com/books?id=JrslMKTgSZwC&pg=PA90 90]}} }}</ref>
The word "algebra" is named after the [[Arabic]] word "''al-jabr''" from the title of the book ''{{Unicode | [[The Compendious Book on Calculation by Completion and Balancing|al-Kitāb al-muḫtaṣar fī ḥisāb al-ğabr wa-l-muqābala]]}}'', meaning ''The book of Summary Concerning Calculating by Transposition and Reduction'', a book written by the [[Islamic mathematics|Persian mathematician]] {{Unicode|[[Muhammad ibn Musa al-Khwarizmi|Muhammad ibn Mūsā al-khwārizmī]]}} in 820. The word ''Al-Jabr'' means ''"reunion"''. The Hellenistic mathematician [[Diophantus]] has traditionally been known as "the father of algebra" but debate now exists as to whether or not Al-Khwarizmi should take that title.<ref>Carl B. Boyer, ''A History of Mathematics, Second Edition'' (Wiley, 1991), pages 178, 181</ref> Those who support Al-Khwarizmi point to the fact that much of his work on [[Reduction (mathematics)|reduction]] is still in use today and that he gave an exhaustive explanation of solving quadratic equations. Those who support [[Diophantus]] point to the fact that the algebra found in ''Al-Jabr'' is more elementary than the algebra found in ''Arithmetica'' and that ''Arithmetica'' is syncopated while ''Al-Jabr'' is fully rhetorical.<ref>Carl B. Boyer, ''A History of Mathematics, Second Edition'' (Wiley, 1991), page 228</ref> Another Persian mathematician, [[Omar Khayyam]], developed [[algebraic geometry]] and found the general geometric solution of the [[cubic equation]]. The Indian mathematicians [[Mahavira (mathematician)|Mahavira]] and [[Bhaskara II]], and the Chinese mathematician [[Zhu Shijie]], solved various cases of cubic, [[quartic equation|quartic]], [[quintic equation|quintic]] and higher-order [[polynomial]] equations.


In India, [[Brahmagupta]] investigated how to solve quadratic equations and systems of equations with several variables in the 7th century CE. Among his innovations were the use of zero and negative numbers in algebraic equations.<ref>{{multiref | {{harvnb|Tanton|2005|pp=9–10}} | {{harvnb|Corry|2024|loc=§ The Equation in India and China}} }}</ref> The Indian mathematicians [[Mahāvīra]] in the 9th century and [[Bhāskara II]] in the 12th century further refined Brahmagupta's methods and concepts.<ref>{{multiref | {{harvnb|Seshadri|2010|p=[https://books.google.com/books?id=w_JdDwAAQBAJ&pg=PA156 156]}} | {{harvnb|Emch|Sridharan|Srinivas|2005|p=[https://books.google.com/books?id=qfJdDwAAQBAJ&pg=PA20 20]}} }}</ref> In 1247, the Chinese mathematician [[Qin Jiushao]] wrote the ''[[Mathematical Treatise in Nine Sections]]'', which includes [[Horner's method|an algorithm]] for the [[Polynomial evaluation|numerical evaluation of polynomials]], including polynomials of higher degrees.<ref>{{multiref | {{harvnb|Smorynski|2007|p=[https://books.google.com/books?id=qY657eFq7UgC&pg=PA137 137]}} | {{harvnb|Zwillinger|2002|p=[https://books.google.com/books?id=gE_MBQAAQBAJ&pg=PA812 812]}} }}</ref>
Another key event in the further development of algebra was the general algebraic solution of the cubic and quartic equations, developed in the mid-16th century. The idea of a [[determinant]] was developed by [[Japanese mathematics|Japanese mathematician]] [[Kowa Seki]] in the 17th century, followed by [[Gottfried Leibniz]] ten years later, for the purpose of solving systems of simultaneous linear equations using [[matrix (mathematics)|matrices]]. [[Gabriel Cramer]] also did some work on matrices and determinants in the 18th century. [[Abstract algebra]] was developed in the 19th century, initially focusing on what is now called [[Galois theory]], and on [[constructible number|constructibility]] issues.


{{multiple image
The stages of the development of symbolic algebra are roughly as follows:
|perrow=2
|total_width=350
|image1=Francois Viete.jpeg
|alt1=Drawing of François Viète
|image2=Frans Hals - Portret van René Descartes (cropped).jpg
|alt2=Painting of René Descartes
|footer=[[François Viète]] (left) and [[René Descartes]] invented a symbolic notation to express equations in an abstract and concise manner.
}}


The Italian mathematician [[Fibonacci]] brought al-Khwarizmi's ideas and techniques to Europe in books including his ''[[Liber Abaci]]''.<ref>{{multiref | {{harvnb|Waerden|2013|pp=32–35}} | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Kvasz|2006|p=293}} }}</ref> In 1545, the Italian polymath [[Gerolamo Cardano]] published his book ''[[Ars Magna (Cardano book)|Ars Magna]]'', which covered many topics in algebra, discussed [[imaginary numbers]], and was the first to present general methods for solving [[Cubic equation|cubic]] and [[Quartic equation|quartic equations]].<ref>{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Kvasz|2006|p=293}} | {{harvnb|Corry|2024|loc=§ Cardano and the Solving of Cubic and Quartic Equations}} | {{harvnb|Miyake|2002|p=[https://books.google.com/books?id=G0P2BwAAQBAJ&pg=PA268 268]}} }}</ref> In the 16th and 17th centuries, the French mathematicians [[François Viète]] and [[René Descartes]] introduced letters and symbols to denote variables and operations, making it possible to express equations in an abstract and concise manner. Their predecessors had relied on verbal descriptions of problems and solutions.<ref>{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Kvasz|2006|pp=291–292, 297–298, 302}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Corry|2024|loc=§ Viète and the Formal Equation, § Analytic Geometry}} }}</ref> Some historians see this development as a key turning point in the history of algebra and consider what came before it as the prehistory of algebra because it lacked the abstract nature based on symbolic manipulation.<ref>{{multiref | {{harvnb|Hazewinkel|1994|p=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA73 73]}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} }}</ref>
* Rhetorical algebra, which was developed by the Babylonians and remained dominant up to the 16th century;
* Geometric constructive algebra, which was emphasised by the [[Vedic civilization|Vedic Indian]] and classical Greek mathematicians;
* Syncopated algebra, as developed by [[Diophantus]], [[Brahmagupta]] and the ''[[Bakhshali Manuscript]]''; and
* Symbolic algebra, which was initiated by [[Abū al-Hasan ibn Alī al-Qalasādī]]<ref name=Qalasadi/> and sees its culmination in the work of [[Gottfried Leibniz]].


[[File:Garrett Birkhoff.jpeg|thumb|alt=Photo of Garrett Birkhoff|[[Garrett Birkhoff]] developed many of the foundational concepts of universal algebra.|left|upright=0.8]]
[[Image:Diophantus-cover.jpg|right|thumb|200px|Cover of the 1621 edition of Diophantus's ''Arithmetica'', translated into [[Latin]] by [[Claude Gaspard Bachet de Méziriac]].]]A timeline of key algebraic developments are as follows:


Many attempts in the 17th and 18th centuries to find general solutions{{efn|A general solution or a [[solution in radicals]] is a [[Closed-form expression|closed-form]] algebraic equation that isolates the variable on one side. For example, the general solution to quadratic equations of the form <math>ax^2 + bx + c = 0</math> is described by the [[quadratic formula]] <math display=block>x = \frac{-b \pm \sqrt {b^2-4ac\ }}{2a}.</math> The absence of general solutions does not mean that there are no numerical solutions.<ref>{{multiref | {{harvnb|Igarashi|Altman|Funada|Kamiyama|2014|p=[https://books.google.com/books?id=58ySAwAAQBAJ&pg=PA103 103]}} | {{harvnb|Sun|Zhang|2020|p=[https://books.google.com/books?id=SZ3hDwAAQBAJ&pg=PA94 94]}} }}</ref> }} to polynomials of degree five and higher failed.<ref name="auto3">{{multiref | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Corry|2024|loc=§ Impasse with Radical Methods}} }}</ref> At the end of the 18th century, the German mathematician [[Carl Friedrich Gauss]] proved the [[fundamental theorem of algebra]], which describes the existence of [[Zero of a function|zeros]] of polynomials of any degree without providing a general solution.<ref name="auto7"/> At the beginning of the 19th century, the Italian mathematician [[Paolo Ruffini]] and the Norwegian mathematician [[Niels Henrik Abel]] were [[Abel–Ruffini theorem|able to show]] that no general solution exists for polynomials of degree five and higher.<ref name="auto3"/> In response to and shortly after their findings, the French mathematician [[Évariste Galois]] developed what came later to be known as [[Galois theory]], which offered a more in-depth analysis of the solutions of polynomials while also laying the foundation of [[group theory]].<ref name="auto2"/> Mathematicians soon realized the relevance of group theory to other fields and applied it to disciplines like geometry and number theory.<ref>{{multiref | {{harvnb|Corry|2024|loc=§ Applications of Group Theory}} | {{harvnb|Bueno|French|2018|pp=[https://books.google.com/books?id=kmZaDwAAQBAJ&pg=PA73 73–75]}} }}</ref>
* Circa 1800 BC: The [[First Babylonian Dynasty|Old Babylonian]] [[Strassburg tablet]] seeks the solution of a quadratic elliptic equation.
* Circa 1600 BC: The ''[[Plimpton 322]]'' tablet gives a table of [[Pythagorean triples]] in [[Babylonia]]n [[Cuneiform script]].
* Circa 800 BC: Indian mathematician [[Baudhayana]], in his ''Baudhayana [[Sulba Sutras|Sulba Sutra]]'', discovers Pythagorean triples algebraically, finds geometric solutions of linear equations and quadratic equations of the forms ax<sup>2</sup> = c and ax<sup>2</sup> + bx = c, and finds two sets of positive integral solutions to a set of simultaneous [[Diophantine equation]]s.
* Circa 600 BC: Indian mathematician [[Apastamba]], in his ''Apastamba Sulba Sutra'', solves the general linear equation and uses simultaneous Diophantine equations with up to five unknowns.
* Circa 300 BC: In Book II of his Elements, [[Euclid]] gives a geometric construction with Euclidean tools for the solution of the quadratic equation for positive real roots. The construction is due to the Pythagorean School of geometry.
* Circa 300 BC: A geometric construction for the solution of the cubic is sought (doubling the cube problem). It is now well known that the general cubic has no such solution using [[Euclidean tools]].
* Circa 100 BC: Algebraic equations are treated in the Chinese mathematics book ''[[The Nine Chapters on the Mathematical Art|Jiuzhang suanshu]]'' (''The Nine Chapters on the Mathematical Art''), which contains solutions of linear equations solved using the [[False position method|rule of double false position]], geometric solutions of quadratic equations, and the solutions of matrices equivalent to the modern method, to solve systems of simultaneous linear equations.
* Circa 100 BC: The ''[[Indian mathematics#Bakhshali Manuscript (200 BCE - 400 CE)|Bakhshali Manuscript]]'' written in [[Middle kingdoms of India|ancient India]] uses a form of algebraic notation using letters of the alphabet and other signs, and contains cubic and quartic equations, algebraic solutions of [[linear equations]] with up to five unknowns, the general algebraic formula for the quadratic equation, and solutions of indeterminate quadratic equations and simultaneous equations.
* Circa 150 AD: [[Hero of Alexandria]] treats algebraic equations in three volumes of mathematics.
* Circa 200: [[Diophantus]], who lived in Egypt and is often considered the "father of algebra", writes his famous ''[[Arithmetica]]'', a work featuring solutions of algebraic equations and on the theory of numbers.
* 499: Indian mathematician [[Aryabhata]], in his treatise ''Aryabhatiya'', obtains whole-number solutions to linear equations by a method equivalent to the modern one, describes the general integral solution of the indeterminate linear equation and gives integral solutions of simultaneous indeterminate linear equations.
* Circa 625: Chinese mathematician [[Wang Xiaotong]] finds numerical solutions of cubic equations.
* 628: Indian mathematician [[Brahmagupta]], in his treatise ''Brahma Sputa Siddhanta'', invents the [[chakravala method|''chakravala'' method]] of solving indeterminate quadratic equations, including [[Pell's equation]], and gives rules for solving linear and quadratic equations.
* 820: The word ''algebra'' is derived from operations described in the treatise written by the [[Persian people|Persian]] mathematician {{Unicode|[[Muhammad ibn Musa al-Khwarizmi|Muḥammad ibn Mūsā al-Ḵwārizmī]]}} titled ''Al-Kitab al-Jabr wa-l-Muqabala'' (meaning "The Compendious Book on Calculation by Completion and Balancing") on the systematic solution of [[linear equation|linear]] and [[quadratic equation]]s. Al-Khwarizmi is often considered as the "father of algebra", much of whose works on reduction was included in the book and added to many methods we have in algebra now.
* Circa 850: [[Persian people|Persian]] mathematician [[al-Mahani]] conceived the idea of reducing geometrical problems such as [[Doubling the cube|duplicating the cube]] to problems in algebra.
* Circa 850: Indian mathematician [[Mahavira (mathematician)|Mahavira]] solves various quadratic, cubic, quartic, quintic and higher-order equations, as well as indeterminate quadratic, cubic and higher-order equations.
* Circa 990: [[Persian people|Persian]] [[Abu Bakr al-Karaji]], in his treatise ''al-Fakhri'', further develops algebra by extending Al-Khwarizmi's methodology to incorporate integral powers and integral roots of unknown quantities. He replaces geometrical operations of algebra with modern arithmetical operations, and defines the [[monomial]]s x, x<sup>2</sup>, x<sup>3</sup>, ... and 1/x, 1/x<sup>2</sup>, 1/x<sup>3</sup>, ... and gives rules for the products of any two of these.
* Circa 1050: Chinese mathematician [[Jia Xian]] finds numerical solutions of polynomial equations.
* 1072: [[Persian people|Persian]] mathematician [[Omar Khayyam]] develops algebraic geometry and, in the ''Treatise on Demonstration of Problems of Algebra'', gives a complete classification of cubic equations with general geometric solutions found by means of intersecting conic sections.
* 1114: Indian mathematician [[Bhaskara]], in his ''Bijaganita'' (''Algebra''), recognizes that a positive number has both a positive and negative [[square root]], and solves various cubic, quartic and higher-order polynomial equations, as well as the general quadratic indeterminant equation.
* 1202: Algebra is introduced to [[Europe]] largely through the work of [[Leonardo Fibonacci]] of [[Pisa]] in his work ''[[Liber Abaci]]''.
* Circa 1300: Chinese mathematician [[Zhu Shijie]] deals with [[polynomial algebra]], solves quadratic equations, simultaneous equations and equations with up to four unknowns, and numerically solves some quartic, [[Quintic equation|quintic]] and higher-order polynomial equations.
* Circa 1400: Indian mathematician [[Madhava of Sangamagramma]] finds [[iterative method]]s for approximate solution of non-linear equations.
* Circa 1450: Arab mathematician [[Abū al-Hasan ibn Alī al-Qalasādī]] took "the first steps toward the introduction of [[Mathematical notation|algebraic symbolism]]." He represented [[Table of mathematical symbols|mathematical symbols]] using characters from the [[Arabic alphabet]].<ref name=Qalasadi>{{MacTutor Biography|id=Al-Qalasadi|title= Abu'l Hasan ibn Ali al Qalasadi}}</ref>
* 1535: Nicolo Fontana [[Tartaglia]] and others mathematicians in Italy independently solved the general cubic equation.<ref name="Stewart">Stewart, Ian, ''Galois Theory, Third Edition'' (Chapman & Hall/CRC Mathematics, 2004).</ref>
* 1545: Girolamo [[Cardano]] publishes ''Ars magna'' -''The great art'' which gives Fontana's solution to the general quartic equation.<ref name="Stewart" />
* 1572: [[Rafael Bombelli]] recognizes the complex roots of the cubic and improves current notation.
* 1591: Francois [[Viete]] develops improved symbolic notation for various powers of an unknown and uses vowels for unknowns and consonants for constants in ''In artem analyticam isagoge''.
* 1631: [[Thomas Harriot]] in a posthumous publication uses exponential notation and is the first to use symbols to indicate "less than" and "greater than".
* 1682: [[Gottfried Leibniz|Gottfried Wilhelm Leibniz]] develops his notion of symbolic manipulation with formal rules which he calls ''characteristica generalis''.
* 1680s: Japanese mathematician [[Kowa Seki]], in his ''Method of solving the dissimulated problems'', discovers the [[determinant]], and [[Bernoulli number]]s.<ref>{{cite web|url=http://www-history.mcs.st-andrews.ac.uk/Biographies/Seki.html|title=Takakazu Seki Kowa|work=MacTutor History of Mathematics archive|author=O'Connor, John J., and Edmund F. Robertson}}</ref>
* 1750: [[Gabriel Cramer]], in his treatise ''Introduction to the analysis of algebraic curves'', states [[Cramer's rule]] and studies [[algebraic curves]], matrices and determinants.
* 1824: [[Niels Henrik Abel]] proved that the general quintic equation is insoluble by radicals.<ref name="Stewart" />
* 1832: Galois theory is developed by [[Évariste Galois]] in his work on abstract algebra.<ref name="Stewart" />


Starting in the mid-19th century, interest in algebra shifted from the study of polynomials associated with elementary algebra towards a more general inquiry into algebraic structures, marking the emergence of [[abstract algebra]]. This approach explored the axiomatic basis of arbitrary algebraic operations.<ref>{{multiref | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Corry|2024|loc=§ Structural Algebra}} | {{harvnb|Hazewinkel|1994|pp=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA73 73–74]}} }}</ref> The invention of new algebraic systems based on different operations and elements accompanied this development, such as [[Boolean algebra]], [[Vector space|vector algebra]], and [[matrix algebra]].<ref>{{multiref | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Tanton|2005|p=10}} | {{harvnb|Corry|2024|loc=§ Matrices, § Quaternions and Vectors}} }}</ref> Influential early developments in abstract algebra were made by the German mathematicians [[David Hilbert]], [[Ernst Steinitz]], and [[Emmy Noether]] as well as the Austrian mathematician [[Emil Artin]]. They researched different forms of algebraic structures and categorized them based on their underlying axioms into types, like groups, rings, and fields.<ref>{{multiref | {{harvnb|Merzlyakov|Shirshov|2020|loc=§ Historical Survey}} | {{harvnb|Corry|2024|loc=§ Hilbert and Steinitz, § Noether and Artin}} | {{harvnb|Hazewinkel|1994|pp=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA73 73–74]}} }}</ref> The idea of the even more general approach associated with universal algebra was conceived by the English mathematician [[Alfred North Whitehead]] in his 1898 book ''A Treatise on Universal Algebra''. Starting in the 1930s, the American mathematician [[Garrett Birkhoff]] expanded these ideas and developed many of the foundational concepts of this field.<ref>{{multiref | {{harvnb|Grätzer|2008|p=[https://books.google.com/books?id=8lNkXPJas4wC&pg=PR7 vii]}} | {{harvnb|Chang|Keisler|1990|p=[https://books.google.com/books?id=uiHq0EmaFp0C&pg=PA603 603]}} | {{harvnb|Knoebel|2011|p=[https://books.google.com/books?id=VWS_sgO2uvgC&pg=PA5 5]}} | {{harvnb|Hazewinkel|1994|pp=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA74 74–75]}} }}</ref> Closely related developments were the formulation of [[model theory]], [[category theory]], [[topological algebra]], [[homological algebra]], [[Lie algebra]]s, [[free algebra]]s, and [[homology groups]].<ref>{{multiref | {{harvnb|Hazewinkel|1994|pp=[https://books.google.com/books?id=PE1a-EIG22kC&pg=PA74 74–75]}} | {{harvnb|Grätzer|2008|p=338}} | {{harvnb|Pratt|2022|loc=§ 6. Free Algebras}} }}</ref>
== See also ==
{{Wikibooks}}
{{wiktionary}}


{{clear}}
* [[List of basic algebra topics]]

* [[List of mathematics articles]]
== Applications ==
* [[Fundamental theorem of algebra]]
The influence of algebra is wide-reaching and includes many branches of mathematics as well as the empirical sciences. Algebraic notation and principles play a key role in [[physics]] and related disciplines to express [[scientific laws]] and solve equations.<ref>{{multiref | {{harvnb|Houston|2004|p=[https://books.google.com/books?id=jsWL_XJt-dMC&pg=PA319 319]}} | {{harvnb|Corrochano|Sobczyk|2011|p=[https://books.google.com/books?id=GUHhBwAAQBAJ&pg=PR17 xvii]}} | {{harvnb|Neri|2019|p=[https://books.google.com/books?id=NMOlDwAAQBAJ&pg=PR12 xii]}} }}</ref> They are also used in fields like [[engineering]], [[economics]], [[computer science]], and [[geography]] to express relationships, solve problems, and model systems.<ref>{{multiref | {{harvnb|Corrochano|Sobczyk|2011|p=[https://books.google.com/books?id=GUHhBwAAQBAJ&pg=PR17 xvii]}} | {{harvnb|Neri|2019|p=[https://books.google.com/books?id=NMOlDwAAQBAJ&pg=PR12 xii]}} | {{harvnb|Aleskerov|Ersel|Piontkovski|2011|pp=[https://books.google.com/books?id=ipcSD8ZGB8cC&pg=PA1 1–9]}} | {{harvnb|Straffin|1980|p=[https://www.jstor.org/stable/2689388 269]}} }}</ref>
* [[Computer algebra system]]

* [[Order of operations]]
=== Other branches of mathematics ===
The algebraization of mathematics is the process of applying algebraic methods and principles to other [[branches of mathematics]]. It happens by employing symbols in the form of variables to express mathematical insights on a more general level, allowing mathematicians to develop formal models describing how objects interact and relate to each other.<ref>{{multiref | {{harvnb|Mancosu|1999|pp=[https://books.google.com/books?id=60qaEePdqcoC&pg=PA84 84–85]}} | {{harvnb|Kleiner|2007|p=[https://books.google.com/books?id=udj-1UuaOiIC&pg=PA100 100]}} | {{harvnb|Pratt|2022|loc=§ 5. Algebraization of Mathematics}} }}</ref> This is possible because the abstract patterns studied by algebra have many concrete applications in fields such as [[geometry]], [[topology]], [[number theory]], and [[calculus]].<ref>{{multiref | {{harvnb|Kleiner|2007|p=[https://books.google.com/books?id=udj-1UuaOiIC&pg=PA100 100]}} | {{harvnb|Pratt|2022|loc=§ 5. Algebraization of Mathematics}} | {{harvnb|Maddocks|2008|p=130}} }}</ref>

[[File:Sphere Quadric.png|thumb|alt=Rendered image of a sphere|The algebraic equation <math>x^2 + y^2 + z^2 = 1</math> describes a [[sphere]] at the [[Origin (mathematics)|origin]] with a radius of 1.]]

Geometry is interested in geometric figures, which can be described with algebraic statements. For example, the equation <math>y = 3x - 7</math> describes a line in two-dimensional space while the equation <math>x^2 + y^2 + z^2 = 1</math> corresponds to a [[sphere]] in three-dimensional space. Of special interest to [[algebraic geometry]] are [[algebraic varieties]],{{efn|Algebraic varieties studied in geometry differ from the more general varieties studied in universal algebra.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 1.4 Cartesian geometry, § 3. Universal Algebra}} | {{harvnb|Danilov|2006|p=[https://books.google.com/books?id=-QMWR-x66XUC&pg=PA174 174]}} }}</ref>}} which are solutions to [[systems of polynomial equations]] that can be used to describe more complex geometric figures.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 5.1 Algebraic Geometry}} | {{harvnb|Danilov|2006|pp=[https://books.google.com/books?id=-QMWR-x66XUC&pg=PA172 172, 174]}} }}</ref> Algebraic reasoning can also solve geometric problems. For example, one can determine whether and where the line described by <math>y = x + 1</math> intersects with the circle described by <math>x^2 + y^2 = 25</math> by solving the system of equations made up of these two equations.<ref>{{harvnb|Vince|2007|p=[https://books.google.com/books?id=B574tQbP6WcC&pg=PA133 133]}}</ref> Topology studies the properties of geometric figures or [[topological space]]s that are preserved under operations of [[continuous deformation]]. [[Algebraic topology]] relies on algebraic theories such as [[group theory]] to classify topological spaces. For example, [[homotopy groups]] classify topological spaces based on the existence of [[Loop (topology)|loops]] or [[Hole#In mathematics|holes]] in them.<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 5.3 Algebraic Topology}} | {{harvnb|Rabadan|Blumberg|2019|pp=[https://books.google.com/books?id=2967DwAAQBAJ&pg=PA49 49–50]}} | {{harvnb|Nakahara|2018|p=[https://books.google.com/books?id=p2C1DwAAQBAJ&pg=PA121 121]}} | {{harvnb|Weisstein|2003|pp=52–53}} }}</ref> Number theory is concerned with the properties of and relations between integers. [[Algebraic number theory]] applies algebraic methods and principles to this field of inquiry. Number theorists employ algebraic expressions to describe general laws, like [[Fermat's Last Theorem]], and analyze how numbers form algebraic structures, such as the [[ring of integers]].<ref>{{multiref | {{harvnb|Pratt|2022|loc=§ 5.2 Algebraic Number Theory}} | {{harvnb|Jarvis|2014|p=[https://books.google.com/books?id=0j0qBAAAQBAJ&pg=PA1 1]}} | {{harvnb|Viterbo|Hong|2011|p=[https://books.google.com/books?id=d89QRR24jbMC&pg=PA127 127]}} }}</ref> The insights of algebra are also relevant to calculus, which utilizes mathematical expressions to examine [[rates of change]] and [[Integral|accumulation]]. It relies on algebra to understand how these expressions can be transformed and what role variables play in them.<ref>{{multiref | {{harvnb|Kilty|McAllister|2018|pp=x, 347, 589}} | {{harvnb|Bressoud|2021|p=[https://books.google.com/books?id=GkgHEAAAQBAJ&pg=PA64 64]}} }}</ref>

[[File:Rubik's cube.svg|thumb|upright=0.8|alt=Picture of Rubik's cube|The faces of a [[Rubik's cube]] can be rotated to change the arrangement of colored patches. The resulting permutations form a group called the [[Rubik's Cube group]].<ref>{{harvnb|Joyner|2008|p=92}}</ref>]]

Abstract algebra has various uses in [[applied mathematics]], ranging from [[electronics]] and [[robotics]] to [[cryptography]].<ref>{{multiref | {{harvnb|Menini|Oystaeyen|2017|p=[https://books.google.com/books?id=3mlQDwAAQBAJ&pg=PR5 v]}} | {{harvnb|Lovett|2015|p=[https://books.google.com/books?id=jRUqCgAAQBAJ&pg=PR9 ix]}} }}</ref> More specific applications are the use of group theory to solve puzzles including [[Sudoku]] and [[Rubik's cube|Rubik's cubes]]<ref>{{harvnb|Terras|2019|pp=63–64, 142}}</ref> and the reliance on algebraic tools to [[Mathematics of paper folding|analyze origami]].<ref>{{harvnb|Hull|2021|pp=[https://books.google.com/books?id=LdX7DwAAQBAJ&pg=PA5 5, 48]}}</ref>

=== Logic ===
[[Logic]] is the study of correct reasoning.<ref>{{harvnb|Hintikka|2019|loc=Lead section, § Nature and Varieties of Logic}}</ref> [[Algebraic logic]] employs algebraic methods to describe and analyze the structures and patterns that underlie [[logical reasoning]].<ref>{{multiref | {{harvnb|Halmos|1956|p=363}} | {{harvnb|Burris|Legris|2021|loc=§ 1. Introduction}} }}</ref> One part of it is interested in understanding the mathematical structures themselves without regard for the concrete consequences they have on the activity of drawing [[inference]]s. Another part investigates how the problems of logic can be expressed in the language of algebra and how the insights obtained through algebraic analysis affect logic.<ref>{{harvnb|Andréka|Németi|Sain|2001|pp=[https://link.springer.com/chapter/10.1007/978-94-017-0452-6_3 133–134]}}</ref>

[[Boolean algebra]] is an influential device in algebraic logic to describe [[propositional logic]].<ref>{{multiref | {{harvnb|Andréka|Madarász|Németi|2020|loc=§ Concrete Algebraic Logic}} | {{harvnb|Pratt|2022|loc=§ 5.4 Algebraic Logic}} | {{harvnb|Plotkin|2012|pp=[https://books.google.com/books?id=-v3xCAAAQBAJ&pg=PA155 155–156]}} | {{harvnb|Jansana|2022|loc=Lead section}} }}</ref> [[Proposition]]s are statements that can be true or false.<ref>{{harvnb|McGrath|Frank|2023|loc=Lead section}}</ref> Propositional logic uses [[logical connectives]] to combine two propositions to form a complex proposition. For example, the connective "if{{nbsp}}... then" can be used to combine the propositions "it rains" and "the streets are wet" to form the complex proposition "if it rains then the streets are wet". Propositional logic is interested in how the [[truth value]] of a complex proposition depends on the truth values of its constituents.<ref>{{multiref | {{harvnb|Boschini|Hansen|Wolf|2022|p=[https://books.google.com/books?id=huZtEAAAQBAJ&pg=PA21 21]}} | {{harvnb|Brody|2006|pp=535–536}} | {{harvnb|Franks|2023|loc=Lead section}} }}</ref> With Boolean algebra, this problem can be addressed by interpreting truth values as numbers: 0 corresponds to false and 1 corresponds to true. Logical connectives are understood as binary operations that take two numbers as input and return the output that corresponds to the truth value of the complex proposition.<ref>{{multiref | {{harvnb|Andréka|Madarász|Németi|2020|loc=§ Concrete Algebraic Logic}} | {{harvnb|Plotkin|2012|pp=[https://books.google.com/books?id=-v3xCAAAQBAJ&pg=PA155 155–156]}} | {{harvnb|Kachroo|Özbay|2018|pp=[https://books.google.com/books?id=qQNbDwAAQBAJ&pg=PA176 176–177]}} }}</ref> Algebraic logic is also interested in how more complex [[Logic#Systems_of_logic|systems of logic]] can be described through algebraic structures and which varieties and quasivarities these algebraic structures belong to.<ref>{{multiref | {{harvnb|Andréka|Madarász|Németi|2020|loc=§ Abstract Algebraic Logic}} | {{harvnb|Jansana|2022|loc=§ 4. Algebras}} }}</ref>

=== Education ===
{{See also|Mathematics education}}

[[File:Balance scale.svg|thumb|upright=1.3|class=skin-invert-image|alt=Diagram of a balance scale|[[Balance scales]] are used in algebra education to help students understand how equations can be transformed to determine unknown values.<ref>{{multiref | {{harvnb|Kieran|2006|p=[https://books.google.com/books?id=OTCsKu0BZ0kC&pg=PA15 15]}} | {{harvnb|Kaput|2018|p=[https://books.google.com/books?id=1GUPEAAAQBAJ&pg=PA186 186]}} |{{harvnb|Gardella|DeLucia|2020|pp=[https://books.google.com/books?id=HBXFDwAAQBAJ&pg=PA19 19–22]}} }}</ref>]]

Algebra education mostly focuses on elementary algebra, which is one of the reasons why elementary algebra is also called school algebra. It is usually not introduced until [[secondary education]] since it requires mastery of the fundamentals of arithmetic while posing new cognitive challenges associated with abstract reasoning and generalization.<ref>{{multiref | {{harvnb|Arcavi|Drijvers|Stacey|2016|p=xiii}} | {{harvnb|Dekker|Dolk|2011|p=[https://books.google.com/books?id=7sVFaMhwackC&pg=PA69 69]}} }}</ref> It aims to familiarize students with the formal side of mathematics by helping them understand mathematical symbolism, for example, how variables can be used to represent unknown quantities. An additional difficulty for students lies in the fact that, unlike arithmetic calculations, algebraic expressions are often difficult to solve directly. Instead, students need to learn how to transform them according to certain laws, often with the goal of determining an unknown quantity.<ref>{{multiref | {{harvnb|Arcavi|Drijvers|Stacey|2016|pp=2–5}} | {{harvnb|Drijvers|Goddijn|Kindt|2011|pp=[https://books.google.com/books?id=7sVFaMhwackC&pg=PA8 8–10, 16–18]}} }}</ref>

Some tools to introduce students to the abstract side of algebra rely on concrete models and visualizations of equations, including geometric analogies, manipulatives including sticks or cups, and "function machines" representing equations as [[flow diagram]]s. One method uses [[balance scales]] as a pictorial approach to help students grasp basic problems of algebra. The mass of some objects on the scale is unknown and represents variables. Solving an equation corresponds to adding and removing objects on both sides in such a way that the sides stay in balance until the only object remaining on one side is the object of unknown mass.<ref>{{multiref | {{harvnb|Kieran|2006|p=[https://books.google.com/books?id=OTCsKu0BZ0kC&pg=PA15 15]}} | {{harvnb|Kaput|2018|p=[https://books.google.com/books?id=1GUPEAAAQBAJ&pg=PA186 186]}} |{{harvnb|Gardella|DeLucia|2020|pp=[https://books.google.com/books?id=HBXFDwAAQBAJ&pg=PA19 19–22]}} | {{harvnb|Star|Foegen|Larson|McCallum|2015|pp=16–17}} }}</ref> [[Word problem (mathematics education)|Word problems]] are another tool to show how algebra is applied to real-life situations. For example, students may be presented with a situation in which Naomi's brother has twice as many apples as Naomi. Given that both together have twelve apples, students are then asked to find an algebraic equation that describes this situation (<math>2x + x = 12</math>) and to determine how many apples Naomi has {{nowrap|(<math>x = 4</math>).<ref>{{multiref | {{harvnb|Arcavi|Drijvers|Stacey|2016|pp=58–59}} | {{harvnb|Drijvers|Goddijn|Kindt|2011|p=[https://books.google.com/books?id=7sVFaMhwackC&pg=PA13 13]}} }}</ref>}}

== See also ==
{{div col|colwidth=30em}}
* [[Algebra over a set]]
* [[Algebra tile]]
* [[Algebraic combinatorics]]
* [[C*-algebra]]
* [[Composition algebra]]
* [[Computer algebra]]
* [[Exterior algebra]]
* [[F-algebra]]
* [[F-coalgebra]]
* [[Heyting algebra]]
* [[Hopf algebra]]
* [[Non-associative algebra]]
* [[Outline of algebra]]
* [[Relational algebra]]
* [[Sigma-algebra]]
* [[Symmetric algebra]]
* [[T-algebra]]
* [[Tensor algebra]]
{{div col end}}


== References ==
== References ==
=== Notes ===
{{reflist}}
{{notelist}}
* Donald R. Hill, ''Islamic Science and Engineering'' (Edinburgh University Press, 1994).

* Ziauddin Sardar, Jerry Ravetz, and Borin Van Loon, ''Introducing Mathematics'' (Totem Books, 1999).
=== Citations ===
* George Gheverghese Joseph, ''The Crest of the Peacock: Non-European Roots of Mathematics'' ([[Penguin Books]], 2000).
{{Reflist}}
* John J O'Connor and Edmund F Robertson, ''[[MacTutor History of Mathematics archive]]'' ([[University of St Andrews]], 2005).

* I.N. Herstein: ''Topics in Algebra''. ISBN 0-471-02371-X
=== Sources ===
* R.B.J.T. Allenby: ''Rings, Fields and Groups''. ISBN 0-340-54440-6
{{Refbegin|30em}}
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* {{cite web |last1=Baranovich |first1=T. M. |title=Algebraic Operation |url=https://encyclopediaofmath.org/wiki/Algebraic_operation |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2023 |archive-date=August 23, 2023 |archive-url=https://web.archive.org/web/20230823194536/https://encyclopediaofmath.org/wiki/Algebraic_operation |url-status=live }}
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* {{cite book |last1=Burgin |first1=Mark |title=Trilogy Of Numbers And Arithmetic - Book 1: History Of Numbers And Arithmetic: An Information Perspective |date=2022 |publisher=World Scientific |isbn=978-981-12-3685-3 |url=https://books.google.com/books?id=rWF2EAAAQBAJ&pg=PA45 |language=en |access-date=January 13, 2024 }}
* {{cite web |last1=Burris |first1=Stanley |last2=Legris |first2=Javier |title=The Algebra of Logic Tradition |url=https://plato.stanford.edu/entries/algebra-logic-tradition/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |access-date=January 22, 2024 |date=2021 |archive-date=January 29, 2024 |archive-url=https://web.archive.org/web/20240129081715/https://plato.stanford.edu/entries/algebra-logic-tradition/ |url-status=live }}
* {{cite book |last1=Chahal |first1=J. S. |title=Fundamentals of Linear Algebra |publisher=CRC Press |isbn=978-0-429-75810-2 |url=https://books.google.com/books?id=BGR8DwAAQBAJ&pg=PT10 |language=en |date=2018 |access-date=August 29, 2024 }}
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* {{cite book |last1=Cohn |first1=P. M. |title=Universal Algebra |publisher=Springer |isbn=978-94-009-8399-1 |url=https://books.google.com/books?id=6tbuCAAAQBAJ&pg=PR13 |language=en |date=2012 |access-date=June 14, 2024 }}
* {{cite book |last1=Cooper |first1=Ellis D. |title=Mathematical Mechanics: From Particle to Muscle |date=2011 |publisher=World Scientific |isbn=978-981-4289-70-2 |url=https://books.google.com/books?id=Fybzl6QB62gC&pg=PA60 |language=en |access-date=January 20, 2024 }}
* {{cite book |last1=Corrochano |first1=Eduardo Bayro |last2=Sobczyk |first2=Garret |title=Geometric Algebra with Applications in Science and Engineering |date=2011 |publisher=Springer |isbn=978-1-4612-0159-5 |url=https://books.google.com/books?id=GUHhBwAAQBAJ&pg=PR17 |language=en |access-date=January 24, 2024 }}
* {{cite web |last1=Corry |first1=Leo |title=Algebra |url=https://www.britannica.com/science/algebra |website=Encyclopædia Britannica |access-date=January 25, 2024 |language=en |date=2024 |archive-date=January 19, 2024 |archive-url=https://web.archive.org/web/20240119233613/https://www.britannica.com/science/algebra |url-status=live }}
* {{cite book |last1=Cox |first1=David A. |last2=Little |first2=John |last3=O'Shea |first3=Donal |title=Ideals, Varieties, and Algorithms: An Introduction to Computational Algebraic Geometry and Commutative Algebra |date=2015 |publisher=Springer |isbn=978-3-319-16721-3 |url=https://books.google.com/books?id=yL7yCAAAQBAJ&pg=PA268 |language=en |access-date=January 21, 2024 }}
* {{cite book |last1=Cresswell |first1=Julia |title=Oxford Dictionary of Word Origins |date=2010 |publisher=Oxford University Press |isbn=978-0-19-954793-7 |url=https://books.google.com/books?id=J4i3zV4vnBAC&pg=PA11 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Danilov |first1=V. I. |title=Algebraic Geometry I: Algebraic Curves, Algebraic Manifolds and Schemes |date=2006 |publisher=Springer |isbn=978-3-540-51995-9 |chapter-url=https://books.google.com/books?id=-QMWR-x66XUC&pg=PA172 |language=en |chapter=II. Algebraic Varieties and Schemes |access-date=January 24, 2024 }}
* {{cite book |last1=Dekker |first1=Truus |last2=Dolk |first2=Maarten |editor1-last=Drijvers |editor1-first=Paul |title=Secondary Algebra Education: Revisiting Topics and Themes and Exploring the Unknown |date=2011 |publisher=Springer |isbn=978-94-6091-334-1 |chapter-url=https://books.google.com/books?id=7sVFaMhwackC&pg=PA5 |language=en |chapter=3. From Arithmetic to Algebra |access-date=January 24, 2024 }}
* {{cite book |last1=Denecke |first1=Klaus |last2=Wismath |first2=Shelly L. |title=Universal Algebra and Applications in Theoretical Computer Science |publisher=CRC Press |isbn=978-1-4822-8583-3 |url=https://books.google.com/books?id=2UlZDwAAQBAJ&pg=PR5 |language=en |date=2018 |access-date=August 30, 2024 }}
* {{cite book |last1=Deo |first1=Satya |title=Algebraic Topology: A Primer |publisher=Springer |isbn=978-981-10-8734-9 |url=https://books.google.com/books?id=HjtRDwAAQBAJ&pg=PA295 |language=en |date=2018 |access-date=August 5, 2024 }}
* {{cite book |last1=Derbyshire |first1=John |title=Unknown Quantity: A Real and Imaginary History of Algebra |date=2006 |publisher=National Academies Press |isbn=978-0-309-09657-7 |chapter-url=https://books.google.com/books?id=mLqaAgAAQBAJ&pg=PT39 |language=en |chapter=2. The Father of Algebra |access-date=January 27, 2024 }}
* {{cite book |last1=Dominich |first1=Sándor |title=The Modern Algebra of Information Retrieval |date=2008 |publisher=Springer |isbn=978-3-540-77659-8 |url=https://books.google.com/books?id=uEedNKV3nlUC&pg=PA19 |language=en |access-date=January 20, 2024 }}
* {{cite book |last1=Drijvers |first1=Paul |last2=Goddijn |first2=Aad |last3=Kindt |first3=Martin |editor1-last=Drijvers |editor1-first=Paul |title=Secondary Algebra Education: Revisiting Topics and Themes and Exploring the Unknown |date=2011 |publisher=Springer |isbn=978-94-6091-334-1 |chapter-url=https://books.google.com/books?id=7sVFaMhwackC&pg=PA5 |language=en |chapter=1. Algebra Education: Exploring Topics and Themes |access-date=January 24, 2024 }}
* {{cite web |last1=Efimov |first1=B. A. |title=Set theory |url=https://encyclopediaofmath.org/wiki/Set_theory |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2014 |archive-date=November 29, 2022 |archive-url=https://web.archive.org/web/20221129153653/https://encyclopediaofmath.org/wiki/Set_theory |url-status=live }}
* {{cite book |last1=Emch |first1=Gerard G. |last2=Sridharan |first2=R. |last3=Srinivas |first3=M. D. |title=Contributions to the History of Indian Mathematics |date=2005 |publisher=Springer |isbn=978-93-86279-25-5 |url=https://books.google.com/books?id=qfJdDwAAQBAJ&pg=PA20 |language=en |access-date=January 27, 2024 }}
* {{cite web |author1=EoM Staff |title=Algebra |url=https://encyclopediaofmath.org/wiki/Algebra |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2017 |archive-date=November 29, 2022 |archive-url=https://web.archive.org/web/20221129153630/https://encyclopediaofmath.org/wiki/Algebra |url-status=live }}
* {{cite book |last1=Fiche |first1=Georges |last2=Hebuterne |first2=Gerard |title=Mathematics for Engineers |date=2013 |publisher=John Wiley & Sons |isbn=978-1-118-62333-6 |url=https://books.google.com/books?id=TqkckiuuXg8C&pg=PT326 |language=en |access-date=January 13, 2024 }}
* {{cite web |last1=Franks |first1=Curtis |title=Propositional Logic |url=https://plato.stanford.edu/entries/logic-propositional/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |access-date=January 22, 2024 |date=2023 |archive-date=January 29, 2024 |archive-url=https://web.archive.org/web/20240129081715/https://plato.stanford.edu/entries/logic-propositional/ |url-status=live }}
* {{cite journal |last1=Gandz |first1=Solomon |title=The Origin of the Term "Algebra" |journal=The American Mathematical Monthly |volume=33 |issue=9 |doi=10.2307/2299605 |date=1926 |pages=437–440 |jstor=2299605 }}
* {{cite book |last1=Gardella |first1=Francis |last2=DeLucia |first2=Maria |title=Algebra for the Middle Grades |date=2020 |publisher=IAP |isbn=978-1-64113-847-5 |url=https://books.google.com/books?id=HBXFDwAAQBAJ&pg=PA19 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Gilbert |first1=William J. |last2=Nicholson |first2=W. Keith |title=Modern Algebra with Applications |date=2004 |publisher=John Wiley & Sons |isbn=978-0-471-46989-6 |url=https://books.google.com/books?id=paINAXYHN8kC&pg=PA4 |language=en |access-date=January 13, 2024 }}
* {{cite book |last1=Golan |first1=Jonathan S. |title=Foundations of Linear Algebra |date=1995 |publisher=Springer |isbn=978-94-015-8502-6 |chapter-url=https://link.springer.com/chapter/10.1007/978-94-015-8502-6_18 |language=en |chapter=Algebras Over A Field |series=Kluwer Texts in the Mathematical Sciences |volume=11 |pages=219–227 |doi=10.1007/978-94-015-8502-6_18 |access-date=January 13, 2024 |archive-date=January 12, 2024 |archive-url=https://web.archive.org/web/20240112171825/https://link.springer.com/chapter/10.1007/978-94-015-8502-6_18 |url-status=live }}
* {{cite book |last1=Goodman |first1=A. W. |title=Algebra From A To Z |volume=1 |date=2001 |publisher=World Scientific |isbn=978-981-310-266-8 |url=https://books.google.com/books?id=TvY7DQAAQBAJ&pg=PA5 |language=en |access-date=March 11, 2024 }}
* {{cite book |last1=Grätzer |first1=George |title=Universal Algebra |date=2008 |publisher=Springer |isbn=978-0-387-77487-9 |url=https://books.google.com/books?id=8lNkXPJas4wC |language=en |edition=2 |access-date=January 27, 2024 }}
* {{cite book |last1=Grillet |first1=Pierre Antoine |title=Abstract Algebra |date=2007 |publisher=Springer |isbn=978-0-387-71568-1 |chapter-url=https://link.springer.com/chapter/10.1007/978-0-387-71568-1_15 |language=en |chapter=Universal Algebra |series=Graduate Texts in Mathematics |volume=242 |pages=559–580 |doi=10.1007/978-0-387-71568-1_15 |access-date=January 13, 2024 |archive-date=January 12, 2024 |archive-url=https://web.archive.org/web/20240112171841/https://link.springer.com/chapter/10.1007/978-0-387-71568-1_15 |url-status=live }}
* {{cite book |last1=Häberle |first1=L. |editor1-last=Fink |editor1-first=Andreas |editor2-last=Lausen |editor2-first=Berthold |editor3-last=Seidel |editor3-first=Wilfried |editor4-last=Ultsch |editor4-first=Alfred |title=Advances in Data Analysis, Data Handling and Business Intelligence |date=2009 |publisher=Springer |isbn=978-3-642-01044-6 |chapter-url=https://books.google.com/books?id=McvSa-cFZCMC&pg=PA640 |language=en |chapter=On Classification of Molecules and Species of Representation Rings |access-date=March 12, 2024 }}
* {{cite journal |last1=Halmos |first1=Paul R. |title=The Basic Concepts of Algebraic Logic |journal=The American Mathematical Monthly |date=1956 |volume=63 |issue=6 |pages=363–387 |doi=10.2307/2309396 |jstor=2309396 |issn=0002-9890}}
* {{cite book |last1=Harrison |first1=Michael |last2=Waldron |first2=Patrick |title=Mathematics for Economics and Finance |date=2011 |publisher=Routledge |isbn=978-1-136-81921-6 |url=https://books.google.com/books?id=_sisAgAAQBAJ&pg=PT464 |language=en |access-date=January 18, 2024 }}
* {{cite book |last1=Hazewinkel |first1=Michiel |title=Encyclopaedia of Mathematics (Set) |date=1994 |publisher=Springer |isbn=978-1-55608-010-4 |url=https://books.google.com/books?id=PE1a-EIG22kC&pg=PA73 |language=en |access-date=January 27, 2024 }}
* {{cite web |author1=HC Staff |title=Arithmetic |url=https://www.ahdictionary.com/word/search.html?q=arithmetic&submit.x=58&submit.y=14 |website=American Heritage Dictionary |publisher=HarperCollins |access-date=October 19, 2023 |date=2022 |archive-date=November 8, 2023 |archive-url=https://web.archive.org/web/20231108181459/https://www.ahdictionary.com/word/search.html?q=arithmetic&submit.x=58&submit.y=14 |url-status=live }}
* {{cite book |last1=Higgins |first1=Peter M. |title=Algebra: A Very Short Introduction |date=2015 |publisher=Oxford University Press |isbn=978-0-19-104746-6 |url=https://books.google.com/books?id=QANiCgAAQBAJ&pg=PA89 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Higham |first1=Nicholas J. |title=Handbook of Writing for the Mathematical Sciences |date=2019 |publisher=SIAM |isbn=978-1-61197-610-6 |edition=3 |url=https://books.google.com/books?id=ferEDwAAQBAJ&pg=PA296 |language=en |access-date=March 17, 2024 }}
* {{cite web |last1=Hintikka |first1=Jaakko J. |author-link=Jaakko Hintikka |title=Philosophy of Logic |url=https://www.britannica.com/topic/philosophy-of-logic |website=Encyclopædia Britannica |access-date=November 21, 2021 |language=en |archive-date=April 28, 2015 |archive-url=https://web.archive.org/web/20150428101732/http://www.britannica.com/EBchecked/topic/346240/philosophy-of-logic |url-status=live |date=2019 }}
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* {{cite book |last1=Houston |first1=Stephen D. |title=The First Writing: Script Invention as History and Process |date=2004 |publisher=Cambridge University Press |isbn=978-0-521-83861-0 |url=https://books.google.com/books?id=jsWL_XJt-dMC&pg=PA319 |language=en }}
* {{cite book |last1=Hull |first1=Thomas C. |title=Origametry: Mathematical Methods in Paper Folding |publisher=Cambridge University Press |isbn=978-1-108-47872-4 |url=https://books.google.com/books?id=LdX7DwAAQBAJ&pg=PA5 |date=2021 |access-date=August 7, 2024 }}
* {{cite book |last1=Igarashi |first1=Yoshihide |last2=Altman |first2=Tom |last3=Funada |first3=Mariko |last4=Kamiyama |first4=Barbara |title=Computing: A Historical and Technical Perspective |date=2014 |publisher=CRC Press |isbn=978-1-4822-2741-3 |url=https://books.google.com/books?id=58ySAwAAQBAJ&pg=PA103 |language=en |access-date=January 29, 2024 }}
* {{cite book |last1=Indurkhya |first1=Bipin |title=Metaphor and Cognition: An Interactionist Approach |date=2013 |publisher=Springer |isbn=978-94-017-2252-0 |chapter-url=https://books.google.com/books?id=foTrCAAAQBAJ&pg=PA217 |language=en |chapter=6.5 Algebras and Structures |access-date=January 21, 2024 }}
* {{cite book |last1=Irving |first1=Ronald S. |title=Integers, Polynomials, and Rings: A Course in Algebra |date=2004 |publisher=Springer |isbn=978-0-387-40397-7 |url=https://books.google.com/books?id=-7OM1OtOFJgC |language=en |access-date=January 20, 2024 }}
* {{cite web |last1=Ivanova |first1=O. A. |title=Ring |url=https://encyclopediaofmath.org/wiki/Ring |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2016 |archive-date=January 1, 2023 |archive-url=https://web.archive.org/web/20230101135941/https://encyclopediaofmath.org/wiki/Ring |url-status=live }}
* {{cite web |last1=Ivanova |first1=O. A. |last2=Smirnov |first2=D. M. |title=Isomorphism |url=https://encyclopediaofmath.org/wiki/Isomorphism |website=Encyclopedia of Mathematics |publisher=Springer |date=2012 |access-date=March 11, 2024 |archive-date=August 6, 2024 |archive-url=https://web.archive.org/web/20240806082014/https://encyclopediaofmath.org/wiki/Isomorphism |url-status=live }}
* {{cite web |last1=Jansana |first1=Ramon |title=Algebraic Propositional Logic |url=https://plato.stanford.edu/entries/logic-algebraic-propositional/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |access-date=January 22, 2024 |date=2022 |archive-date=December 20, 2016 |archive-url=https://web.archive.org/web/20161220155433/https://plato.stanford.edu/entries/logic-algebraic-propositional/ |url-status=live }}
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* {{cite book |last1=Jenkins |first1=Everett |title=The Muslim Diaspora (Volume 1, 570-1500): A Comprehensive Chronology of the Spread of Islam in Asia, Africa, Europe and the Americas |date=2010 |publisher=McFarland |isbn=978-0-7864-4713-8 |url=https://books.google.com/books?id=giEkCQAAQBAJ&pg=PA82 |language=en |access-date=January 28, 2024 }}
* {{cite book |last1=Joyner |first1=David |title=Adventures in Group Theory: Rubik's Cube, Merlin's Machine, and Other Mathematical Toys |publisher=Johns Hopkins University Press |isbn=978-0-8018-9012-3 |edition=2 |date=2008 }}
* {{cite book |last1=Kachroo |first1=Pushkin |last2=Özbay |first2=Kaan M. A. |title=Feedback Control Theory for Dynamic Traffic Assignment |date=2018 |publisher=Springer |isbn=978-3-319-69231-9 |url=https://books.google.com/books?id=qQNbDwAAQBAJ&pg=PA176 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Kaput |first1=James J. |editor1-last=Wagner |editor1-first=Sigrid |editor2-last=Kieran |editor2-first=Carolyn |title=Research Issues in the Learning and Teaching of Algebra: the Research Agenda for Mathematics Education, Volume 4 |publisher=Routledge |isbn=978-1-135-43414-4 |chapter-url=https://books.google.com/books?id=1GUPEAAAQBAJ&pg=PA186 |language=en |chapter=Linking Representations in the Symbol Systems of Algebra |date=2018 |access-date=August 8, 2024 }}
* {{cite web |last1=Kargapolov |first1=M. I. |last2=Merzlyakov |first2=Yu. I. |title=Group |url=https://encyclopediaofmath.org/wiki/Group |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2016 |archive-date=December 5, 2022 |archive-url=https://web.archive.org/web/20221205014207/https://encyclopediaofmath.org/wiki/Group |url-status=live }}
* {{cite book |last1=Khattar |first1=Dinesh |last2=Agrawal |first2=Neha |title=Group Theory |date=2023 |publisher=Springer and Ane Books Pvt. Ltd. |isbn=978-3-031-21307-6 |url=https://books.google.com/books?id=7-nIEAAAQBAJ&pg=PA4 |language=en |access-date=January 20, 2024 }}
* {{cite book |last1=Kieran |first1=Carolyn |editor1-last=Gutiérrez |editor1-first=Angel |editor2-last=Boero |editor2-first=Paolo |title=Handbook of Research on the Psychology of Mathematics Education: Past, Present and Future |publisher=Sense Publishers |isbn=978-90-77874-19-6 |chapter-url=https://books.google.com/books?id=OTCsKu0BZ0kC&pg=PA15 |language=en |chapter=Research on the Learning and Teaching of Algebra |date=2006 |access-date=August 8, 2024 }}
* {{cite book |last1=Kilty |first1=Joel |last2=McAllister |first2=Alex |title=Mathematical Modeling and Applied Calculus |date=2018 |publisher=Oxford University Press |isbn=978-0-19-255813-8 |url=https://books.google.com/books?id=YVRuDwAAQBAJ&pg=PA347 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Kleiner |first1=Israel |title=A History of Abstract Algebra |date=2007 |publisher=Springer |isbn=978-0-8176-4685-1 |url=https://books.google.com/books?id=udj-1UuaOiIC&pg=PA100 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Knoebel |first1=Arthur |title=Sheaves of Algebras Over Boolean Spaces |date=2011 |publisher=Springer |isbn=978-0-8176-4218-1 |url=https://books.google.com/books?id=VWS_sgO2uvgC&pg=PA5 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Kramer |first1=Jürg |last2=Pippich |first2=Anna-Maria von |title=From Natural Numbers to Quaternions |date=2017 |publisher=Springer |isbn=978-3-319-69429-0 |url=https://books.google.com/books?id=nvM-DwAAQBAJ&pg=PA49 |language=en |access-date=January 20, 2024 }}
* {{cite journal |last1=Kvasz |first1=L. |title=The History of Algebra and the Development of the Form of Its Language |journal=Philosophia Mathematica |date=2006 |volume=14 |issue=3 |pages=287–317 |doi=10.1093/philmat/nkj017|doi-access=free |issn=1744-6406}}
* {{cite book |last1=Lal |first1=Ramji |title=Algebra 2: Linear Algebra, Galois Theory, Representation Theory, Group Extensions and Schur Multiplier |publisher=Springer |isbn=978-981-10-4256-0 |url=https://books.google.com/books?id=FwPNDgAAQBAJ&pg=PA31 |language=en |date=2017 }}
* {{cite book |last1=Lamagna |first1=Edmund A. |title=Computer Algebra: Concepts and Techniques |date=2019 |publisher=CRC Press |isbn=978-1-351-60583-0 |url=https://books.google.com/books?id=8PSDDwAAQBAJ&pg=PA150 |language=en |access-date=January 16, 2024 }}
* {{cite book |author1=Library of Congress |title=Library of Congress Classification: Class Q - Science |publisher=Library of Congress |url=https://www.loc.gov/aba/cataloging/classification/lcco/lcco_q.pdf |access-date=March 17, 2024 |archive-date=April 5, 2024 |archive-url=https://web.archive.org/web/20240405210545/https://www.loc.gov/aba/cataloging/classification/lcco/lcco_q.pdf |url-status=live }}
* {{cite book |last1=Lovett |first1=Stephen |title=Abstract Algebra: Structures and Applications |publisher=CRC Press |isbn=978-1-4822-4891-3 |url=https://books.google.com/books?id=jRUqCgAAQBAJ&pg=PR9 |language=en |date=2015 |access-date=July 27, 2024 }}
* {{cite book |last1=Lukas |first1=Andre |title=The Oxford Linear Algebra for Scientists |publisher=Oxford University Press |isbn=978-0-19-258347-5 |url=https://books.google.com/books?id=1-dvEAAAQBAJ&pg=PA47 |language=en |date=2022 }}
* {{cite book |last1=Maddocks |first1=J. R. |editor1-last=Lerner |editor1-first=Brenda Wilmoth |editor2-last=Lerner |editor2-first=K. Lee |title=The Gale Encyclopedia of Science |date=2008 |publisher=Thompson Gale |isbn=978-1-4144-2877-2 |edition=4th |chapter=Algebra |url=https://www.encyclopedia.com/science-and-technology/mathematics/mathematics/algebra |access-date=January 13, 2024 |archive-date=January 12, 2024 |archive-url=https://web.archive.org/web/20240112102551/https://www.encyclopedia.com/science-and-technology/mathematics/mathematics/algebra |url-status=live }}
* {{cite book |last1=Majewski |first1=Miroslaw |title=MuPAD Pro Computing Essentials |date=2004 |publisher=Springer |isbn=978-3-540-21943-9 |edition=2}}
* {{cite book |last1=Mal’cev |first1=A. I. |title=Algebraic Systems |date=1973 |publisher=Springer |isbn=978-3-642-65374-2 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-642-65374-2_5 |language=en |chapter=Quasivarieties |pages=210–266 |doi=10.1007/978-3-642-65374-2_5 |access-date=January 21, 2024 |archive-date=June 18, 2018 |archive-url=https://web.archive.org/web/20180618183135/https://link.springer.com/chapter/10.1007%2F978-3-642-65374-2_5 |url-status=live }}
* {{cite book |last1=Mancosu |first1=Paolo |title=Philosophy of Mathematics and Mathematical Practice in the Seventeenth Century |date=1999 |publisher=Oxford University Press |isbn=978-0-19-513244-1 |url=https://books.google.com/books?id=60qaEePdqcoC&pg=PA84 |language=en |access-date=January 24, 2024 }}
* {{cite web |last1=Markushevich |first1=A. I. |title=Polynomial |url=https://encyclopediaofmath.org/wiki/Polynomial |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2015 |archive-date=August 6, 2024 |archive-url=https://web.archive.org/web/20240806082025/https://encyclopediaofmath.org/wiki/Polynomial |url-status=live }}
* {{cite book |last1=Maxwell |first1=E. A. |title=Algebraic Structure and Matrices Book 2 |date=2009 |publisher=Syracuse University Press |isbn=978-0-521-10905-5 |url=https://books.google.com/books?id=yD0irRUE_u4C&pg=PA73 |language=en |access-date=January 20, 2024 }}
* {{cite web |last1=McGrath |first1=Matthew |last2=Frank |first2=Devin |title=Propositions |url=https://plato.stanford.edu/entries/propositions/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |access-date=January 22, 2024 |date=2023 |archive-date=January 29, 2024 |archive-url=https://web.archive.org/web/20240129081718/https://plato.stanford.edu/entries/propositions/ |url-status=live }}
* {{cite book |last1=McKeague |first1=Charles P. |title=Elementary Algebra |publisher=Academic Press |isbn=978-1-4832-6384-7 |url=https://books.google.com/books?id=sq7iBQAAQBAJ&pg=PA148 |language=en |date=1986 }}
* {{cite book |last1=McKeague |first1=Charles P. |title=Intermediate Algebra: A Text/Workbook |date=2014 |publisher=Academic Press |isbn=978-1-4832-1417-7 |url=https://books.google.com/books?id=nI7iBQAAQBAJ&pg=PA386 |language=en |access-date=January 16, 2024 }}
* {{cite book |last1=McWeeny |first1=R. |title=Symmetry: An Introduction to Group Theory and Its Applications |date=2002 |publisher=Courier Corporation |isbn=978-0-486-42182-7 |url=https://books.google.com/books?id=x3fjIXY93TsC&pg=PA6 |language=en |access-date=January 20, 2024 }}
* {{cite book |last1=Menini |first1=Claudia |last2=Oystaeyen |first2=Freddy Van |url=https://books.google.com/books?id=3mlQDwAAQBAJ&pg=PA722 |title=Abstract Algebra: A Comprehensive Treatment |date=2017 |publisher=[[CRC Press]] |isbn=978-1-4822-5817-2 |language=en |access-date=January 27, 2024 }}
* {{cite web |last1=Merzlyakov |first1=Yu. I. |last2=Shirshov |first2=A. I. |title=Algebra(2) |url=https://encyclopediaofmath.org/wiki/Algebra(2) |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 11, 2023 |date=2020 |archive-date=April 7, 2023 |archive-url=https://web.archive.org/web/20230407165656/https://encyclopediaofmath.org/wiki/Algebra(2) |url-status=live }}
* {{cite book |last1=Mirakhor |first1=Abbas |last2=Krichene |first2=Noureddine |title=Introductory Mathematics and Statistics for Islamic Finance |publisher=John Wiley & Sons |isbn=978-1-118-77972-9 |url=https://books.google.com/books?id=G6XNAwAAQBAJ&pg=PT107 |language=en |date=2014 |access-date=August 7, 2024 }}
* {{cite book |last1=Mishra |first1=Sanjay |title=Fundamentals of Mathematics: Algebra |publisher=Pearson India |isbn=978-93-325-5891-5 |language=en |date=2016 }}
* {{cite book |last1=Miyake |first1=Katsuya |editor1-last=Kanemitsu |editor1-first=Shigeru |editor2-last=Jia |editor2-first=Chaohua |title=Number Theoretic Methods: Future Trends |publisher=Springer |isbn=978-1-4419-5239-4 |chapter-url=https://books.google.com/books?id=G0P2BwAAQBAJ&pg=PA268 |chapter=Some Aspects on Interactions between Algebraic Number Theory and Analytic Number Theory |date=2002 |access-date=August 7, 2024 }}
* {{cite book |last1=Mortensen |first1=C. E. |title=Inconsistent Mathematics |date=2013 |publisher=Springer |isbn=978-94-015-8453-1 |url=https://books.google.com/books?id=KYDrCAAAQBAJ&pg=PA73 |language=en |access-date=January 18, 2024 }}
* {{cite book |last1=Murthy |first1=Swamy and |title=Algebra: Abstract and Modern |publisher=Pearson Education India |isbn=978-93-325-0993-1 |url=https://books.google.com/books?id=CBc8BAAAQBAJ&pg=PA3 |language=en |date=2012 |access-date=August 5, 2024 }}
* {{cite book |last1=Musielak |first1=Dora |title=Sophie Germain: Revolutionary Mathematician |date=2020 |publisher=Springer |isbn=978-3-030-38375-6 |url=https://books.google.com/books?id=iqHYDwAAQBAJ&pg=PA36 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Musser |first1=Gary L. |last2=Peterson |first2=Blake E. |last3=Burger |first3=William F. |title=Mathematics for Elementary Teachers: A Contemporary Approach |date=2013 |publisher=John Wiley & Sons |isbn=978-1-118-48700-6 |url=https://books.google.com/books?id=8jh7DwAAQBAJ |language=en |access-date=March 11, 2024 }}
* {{cite web |author1=MW Staff |title=Definition of Arithmetic |url=https://www.merriam-webster.com/dictionary/arithmetic |website=Merriam-Webster |access-date=October 19, 2023 |language=en |date=2023 |archive-date=November 14, 2023 |archive-url=https://web.archive.org/web/20231114193352/https://www.merriam-webster.com/dictionary/arithmetic |url-status=live }}
* {{cite book |last1=Nakahara |first1=Mikio |title=Geometry, Topology and Physics |date=2018 |publisher=Taylor & Francis |isbn=978-1-4200-5694-5 |url=https://books.google.com/books?id=p2C1DwAAQBAJ&pg=PA121 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Negro |first1=Luca Dal |title=Waves in Complex Media |date=2022 |publisher=Cambridge University Press |isbn=978-1-107-03750-2 |url=https://books.google.com/books?id=MIdoEAAAQBAJ&pg=PA365 |language=en |access-date=January 21, 2024 }}
* {{cite book |last1=Neri |first1=Ferrante |title=Linear Algebra for Computational Sciences and Engineering |date=2019 |publisher=Springer |isbn=978-3-030-21321-3 |url=https://books.google.com/books?id=NMOlDwAAQBAJ&pg=PR12 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Nicholson |first1=W. Keith |title=Introduction to Abstract Algebra |publisher=John Wiley & Sons |isbn=978-1-118-13535-8 |url=https://books.google.com/books?id=w-GaLpapRcEC&pg=PA70 |language=en |date=2012 |access-date=August 30, 2024 }}
* {{cite journal |last1=Oaks |first1=Jeffrey A. |last2=Alkhateeb |first2=Haitham M. |title=Simplifying equations in Arabic algebra |journal=Historia Mathematica |volume=34 |issue=1 |doi=10.1016/j.hm.2006.02.006 |date=2007 |pages=45–61 }}
* {{cite book |last1=Olver |first1=Peter J. |title=Classical Invariant Theory |date=1999 |publisher=Cambridge University Press |isbn=978-0-521-55821-1 |url=https://books.google.com/books?id=1GlHYhNRAqEC&pg=PA55 |language=en |access-date=March 12, 2024 }}
* {{cite book |last1=Ono |first1=Hiroakira |title=Proof Theory and Algebra in Logic |publisher=Springer |isbn=978-981-13-7997-0 |url=https://books.google.com/books?id=SR2nDwAAQBAJ&pg=PA84 |language=en |date=2019 }}
* {{cite web |url=http://www.lexico.com/definition/algebra |archive-url=https://web.archive.org/web/20131120000000/http://www.lexico.com/definition/algebra |url-status=dead |archive-date=November 20, 2013 |title=Algebra |website=[[Lexico]] |publisher=[[Oxford University Press]] |author=OUP Staff }}
* {{cite book |last1=Ovchinnikov |first1=Sergei |title=Number Systems |date=2015 |publisher=American Mathematical Society |isbn=978-1-4704-2018-5 |url=https://books.google.com/books?id=UMbXBgAAQBAJ&pg=PA27 |language=en |access-date=January 20, 2024 }}
* {{cite book |last1=Pickover |first1=Clifford A. |title=The Math Book: From Pythagoras to the 57th Dimension, 250 Milestones in the History of Mathematics |date=2009 |publisher=Sterling Publishing Company, Inc. |isbn=978-1-4027-5796-9 |url=https://books.google.com/books?id=JrslMKTgSZwC&pg=PA90 |language=en |access-date=January 28, 2024 }}
* {{cite book |last1=Plotkin |first1=B. |title=Universal Algebra, Algebraic Logic, and Databases |date=2012 |publisher=Springer |isbn=978-94-011-0820-1 |url=https://books.google.com/books?id=-v3xCAAAQBAJ&pg=PA155 |language=en |access-date=January 24, 2024 }}
* {{cite web |last1=Pratt |first1=Vaughan |title=Algebra |url=https://plato.stanford.edu/entries/algebra/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |access-date=January 11, 2024 |date=2022 |archive-date=January 29, 2024 |archive-url=https://web.archive.org/web/20240129081755/https://plato.stanford.edu/entries/algebra/ |url-status=live }}
* {{cite book |last1=Rabadan |first1=Raul |last2=Blumberg |first2=Andrew J. |title=Topological Data Analysis for Genomics and Evolution: Topology in Biology |date=2019 |publisher=Cambridge University Press |isbn=978-1-107-15954-9 |url=https://books.google.com/books?id=2967DwAAQBAJ&pg=PA49 |language=en |access-date=January 24, 2024 }}
* {{cite book |last1=Ricardo |first1=Henry |title=A Modern Introduction to Linear Algebra |publisher=CRC Press |isbn=978-1-4398-9461-3 |url=https://books.google.com/books?id=s7bMBQAAQBAJ&pg=PA389 |language=en |date=2009 |access-date=August 29, 2024 }}
* {{cite book |last1=Rohde |first1=Ulrich L. |last2=Jain |first2=G. C. |last3=Poddar |first3=Ajay K. |last4=Ghosh |first4=A. K. |title=Introduction to Differential Calculus: Systematic Studies with Engineering Applications for Beginners |date=2012 |publisher=John Wiley & Sons |isbn=978-1-118-13014-8 |url=https://books.google.com/books?id=vk2XbZpsBOwC&pg=PT89 |language=en |access-date=January 16, 2024 }}
* {{cite book |last1=Romanowski |first1=Perry |editor1-last=Lerner |editor1-first=Brenda Wilmoth |editor2-last=Lerner |editor2-first=K. Lee |title=The Gale Encyclopedia of Science |date=2008 |publisher=Thompson Gale |isbn=978-1-4144-2877-2 |edition=4th |chapter=Arithmetic |url=https://www.encyclopedia.com/science-and-technology/mathematics/mathematics/arithmetic |access-date=January 13, 2024 |archive-date=November 1, 2023 |archive-url=https://web.archive.org/web/20231101124957/https://www.encyclopedia.com/science-and-technology/mathematics/mathematics/arithmetic |url-status=live }}
* {{cite book |last1=Rowen |first1=Louis Halle |title=Graduate Algebra: Commutative View: Commutative View |publisher=American Mathematical Society |isbn=978-0-8218-0570-1 |url=https://books.google.com/books?id=AhEPCgAAQBAJ&pg=PA12 |language=en |date=2006 |access-date=June 14, 2024 }}
* {{cite book |last1=Saikia |first1=Promode Kumar |title=Linear Algebra |publisher=Pearson Education India |isbn=978-81-317-4276-1 |url=https://books.google.com/books?id=KhM7BAAAQBAJ&pg=PA1 |language=en |date=2008 |access-date=August 5, 2024 }}
* {{cite book |last1=Seshadri |first1=C. S. |title=Studies in the History of Indian Mathematics |date=2010 |publisher=Springer |isbn=978-93-86279-49-1 |url=https://books.google.com/books?id=w_JdDwAAQBAJ&pg=PA156 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Sialaros |first1=Michalis |title=Revolutions and Continuity in Greek Mathematics |date=2018 |publisher=Walter de Gruyter GmbH & Co KG |isbn=978-3-11-056527-0 |url=https://books.google.com/books?id=2PZYDwAAQBAJ&pg=PT55 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Silvia |first1=M. T. |last2=Robinson |first2=E. A. |title=Deconvolution of Geophysical Time Series in the Exploration for Oil and Natural Gas |date=1979 |publisher=Elsevier |isbn=978-0-08-086864-6 |url=https://books.google.com/books?id=Ecgfjh-MpU0C&pg=PA82 |language=en |access-date=January 21, 2024 }}
* {{cite web |last1=Smirnov |first1=D. M. |title=Universal Algebra |url=https://encyclopediaofmath.org/wiki/Universal_algebra |website=Encyclopedia of Mathematics |publisher=Springer |date=2020 |access-date=August 30, 2024 |archive-date=March 1, 2024 |archive-url=https://web.archive.org/web/20240301115432/https://encyclopediaofmath.org/wiki/Universal_algebra |url-status=live }}
* {{cite book |last1=Smith |first1=Jonathan D. H. |title=Introduction to Abstract Algebra |publisher=CRC Press |isbn=978-1-4987-3162-1 |url=https://books.google.com/books?id=MXu9CgAAQBAJ&pg=PA161 |language=en |date=2015 |access-date=June 14, 2024 }}
* {{cite book |last1=Smorynski |first1=Craig |title=History of Mathematics: A Supplement |date=2007 |publisher=Springer |isbn=978-0-387-75481-9 |url=https://books.google.com/books?id=qY657eFq7UgC&pg=PA137 |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Sneyd |first1=James |last2=Fewster |first2=Rachel M. |last3=McGillivray |first3=Duncan |title=Mathematics and Statistics for Science |publisher=Springer |isbn=978-3-031-05318-4 |url=https://books.google.com/books?id=zqd3EAAAQBAJ&pg=PA211 |language=en |date=2022 }}
* {{cite web |last1=Sobolev |first1=S. K. |title=Constant |url=https://encyclopediaofmath.org/wiki/Algebraic_logic |website=Encyclopedia of Mathematics |publisher=Springer |access-date=October 23, 2023 |date=2015 |archive-date=January 24, 2024 |archive-url=https://web.archive.org/web/20240124094606/https://encyclopediaofmath.org/wiki/Algebraic_logic |url-status=live }}
* {{cite book |last1=Solomon |first1=Bruce |title=Linear Algebra, Geometry and Transformation |publisher=CRC Press |isbn=978-1-4822-9930-4 |url=https://books.google.com/books?id=BpvSBQAAQBAJ&pg=PA57 |language=en |date=2014 |access-date=August 29, 2024 }}
* {{cite book |last1=Sorell |first1=Tom |title=Descartes: A Very Short Introduction |date=2000 |publisher=Oxford University Press |isbn=978-0-19-285409-4 |url=https://books.google.com/books?id=EksSDAAAQBAJ&pg=PA19 |language=en |access-date=March 11, 2024 }}
* {{cite book |last1=Star |first1=Jon R. |last2=Foegen |first2=Anne |last3=Larson |first3=Matthew R. |last4=McCallum |first4=William G. |last5=Porath |first5=Jane |last6=Zbiek |first6=Rose Mary |title=Teaching Strategies for Improving Algebra Knowledge in Middle and High School Students |publisher=U.S. Department of Education / Institute of Education Sciences |date=2015 |oclc=5867417164 }}
* {{cite journal |last1=Straffin |first1=Philip D. |title=Linear Algebra in Geography: Eigenvectors of Networks |journal=Mathematics Magazine |date=1980 |volume=53 |issue=5 |pages=269–276 |doi=10.2307/2689388 |jstor=2689388 |url=https://www.jstor.org/stable/2689388 |issn=0025-570X }}
* {{cite book |last1=Sullivan |first1=Michael |title=Finite Mathematics: An Applied Approach |date=2010 |publisher=John Wiley & Sons |isbn=978-0-470-87639-8 |url=https://books.google.com/books?id=6NKaDwAAQBAJ&pg=PA53 |language=en |access-date=January 18, 2024 }}
* {{cite book |last1=Sun |first1=Shuyu |last2=Zhang |first2=Tao |title=Reservoir Simulations: Machine Learning and Modeling |date=2020 |publisher=Gulf Professional Publishing |isbn=978-0-12-820962-2 |url=https://books.google.com/books?id=SZ3hDwAAQBAJ&pg=PA94 |language=en |access-date=January 29, 2024 }}
* {{cite book |last1=Tan |first1=Kiat Shi |last2=Steeb |first2=Willi-Hans |last3=Hardy |first3=Yorick |title=SymbolicC++:An Introduction to Computer Algebra Using Object-Oriented Programming: An Introduction to Computer Algebra Using Object-Oriented Programming |date=2012 |publisher=Springer |isbn=978-1-4471-0405-6 |url=https://books.google.com/books?id=UDb0BwAAQBAJ&pg=PA306 |language=en |access-date=January 16, 2024 }}
* {{cite book |last1=Tanton |first1=James |title=Encyclopedia of Mathematics |date=2005 |publisher=Facts On File |isbn=978-0-8160-5124-3}}
* {{cite book |last1=Terras |first1=Audrey |title=Abstract Algebra with Applications |publisher=Cambridge University Press |isbn=978-1-107-16407-9 |date=2019 }}
* {{cite book |last1=Tsokos |first1=Chris P. |last2=Wooten |first2=Rebecca D. |title=The Joy of Finite Mathematics: The Language and Art of Math |publisher=Academic Press |isbn=978-0-12-802985-5 |url=https://books.google.com/books?id=zu7HBQAAQBAJ&pg=PA451 |language=en |date=2015 }}
* {{cite book |last1=Valenza |first1=Robert J. |title=Linear Algebra: An Introduction to Abstract Mathematics |publisher=Springer |isbn=978-1-4612-0901-0 |url=https://books.google.com/books?id=7x8MCAAAQBAJ&pg=PR7 |language=en |date=2012 |access-date=August 29, 2024 }}
* {{cite book |last1=Vince |first1=John |title=Vector Analysis for Computer Graphics |publisher=Springer |isbn=978-1-84628-803-6 |url=https://books.google.com/books?id=B574tQbP6WcC&pg=PA133 |language=en |date=2007 |access-date=August 5, 2024 }}
* {{cite book |last1=Viterbo |first1=Emanuele |last2=Hong |first2=Yi |editor1-last=Hlawatsch |editor1-first=Franz |editor2-last=Matz |editor2-first=Gerald |title=Wireless Communications Over Rapidly Time-Varying Channels |date=2011 |publisher=Academic Press |isbn=978-0-08-092272-0 |chapter-url=https://books.google.com/books?id=d89QRR24jbMC&pg=PA127 |language=en |chapter=3.4 Algebraic Number Theory |access-date=January 24, 2024 }}
* {{cite web |last1=Voitsekhovskii |first1=M. I. |title=Linear Equation |url=https://encyclopediaofmath.org/wiki/Linear_equation |website=Encyclopedia of Mathematics |publisher=Springer |access-date=January 10, 2024 |date=2011 |archive-date=November 23, 2023 |archive-url=https://web.archive.org/web/20231123235759/https://encyclopediaofmath.org/wiki/Linear_equation |url-status=live }}
* {{cite book |last1=Waerden |first1=Bartel L. van der |title=A History of Algebra: From al-Khwārizmī to Emmy Noether |date=2013 |publisher=Springer |isbn=978-3-642-51599-6 |url=https://books.google.com/books?id=W6DwCAAAQBAJ |language=en |access-date=January 27, 2024 }}
* {{cite book |last1=Wagner |first1=Sigrid |last2=Kieran |first2=Carolyn |title=Research Issues in the Learning and Teaching of Algebra: The Research Agenda for Mathematics Education |volume=4 |date=2018 |publisher=Routledge |isbn=978-1-135-43421-2 |url=https://books.google.com/books?id=uW4ECwAAQBAJ&pg=PT225 |language=en |access-date=January 13, 2024 }}
* {{cite book |last1=Walz |first1=Guido |title=Lexikon der Mathematik: Band 1: A bis Eif |date=2016 |publisher=Springer |isbn=978-3-662-53498-4 |url=https://www.spektrum.de/lexikon/mathematik/algebra/12062 |language=de |chapter=Algebra |access-date=January 13, 2024 |archive-date=January 12, 2024 |archive-url=https://web.archive.org/web/20240112171819/https://www.spektrum.de/lexikon/mathematik/algebra/12062 |url-status=live |trans-title=Encyclopedia of Mathematics: Volume 1: A to Eif }}
* {{cite book |last1=Weisstein |first1=Eric W. |title=CRC Concise Encyclopedia of Mathematics |date=2003 |publisher=Chapman & Hall/CRC |isbn=978-1-58488-347-0 |edition=2nd}}
* {{cite book |last1=Whitelaw |first1=T. A. |title=Introduction to Abstract Algebra, Third Edition |publisher=CRC Press |isbn=978-0-7514-0147-9 |url=https://books.google.com/books?id=f2hyf0QoB_0C&pg=PA61 |language=en |date=1995 }}
* {{cite book |last1=Williams |first1=G. Arnell |title=Algebra the Beautiful: An Ode to Math's Least-Loved Subject |date=2022 |publisher=Basic Books |isbn=978-1-5416-0070-6 |url=https://books.google.com/books?id=581CEAAAQBAJ&pg=PT62 |language=en |access-date=March 11, 2024 }}
* {{cite book |last1=Young |first1=Cynthia Y. |title=Precalculus |date=2010 |publisher=John Wiley & Sons |isbn=978-0-471-75684-2 |url=https://books.google.com/books?id=9HRLAn326zEC&pg=RA1-PA999 |language=en |access-date=January 16, 2024 }}
* {{cite book |last1=Young |first1=Cynthia Y. |title=Precalculus |date=2023 |publisher=John Wiley & Sons |isbn=978-1-119-86940-5 |url=https://books.google.com/books?id=pMSZEAAAQBAJ&pg=PA714 |language=en |access-date=January 18, 2024 }}
* {{cite web |author1=zbMATH Open |title=Classification |url=https://zbmath.org/classification/ |website=zbMATH Open |publisher=Mathematical Reviews and zbMATH Open |access-date=March 17, 2024 |language=en |date=2024 |archive-date=July 19, 2020 |archive-url=https://web.archive.org/web/20200719184539/https://zbmath.org/classification/ |url-status=live }}
* {{cite book |last1=Zwillinger |first1=Daniel |title=CRC Standard Mathematical Tables and Formulae |date=2002 |publisher=CRC Press |isbn=978-1-4200-3534-6 |url=https://books.google.com/books?id=gE_MBQAAQBAJ&pg=PA812 |language=en |access-date=January 27, 2024 }}
{{Refend}}


== External links ==
== External links ==
{{Wikiquote}}
*[http://www.gresham.ac.uk/event.asp?PageId=45&EventId=620 4000 Years of Algebra], lecture by Robin Wilson, at [[Gresham College]], 17th October 2007 (available for MP3 and MP4 download, as well as a text file).
*{{sep entry|algebra|Algebra|Vaughan Pratt}}
{{Wiktionary|algebra}}
{{Wikibooks|Algebra}}
{{Mathematics-footer}}
{{Algebra-footer}}
{{EB1911 poster|Algebra}}


[[Category:Algebra| ]]
{{Algebra |expanded}}
{{Polynomials}}
[[Category:Arabic words and phrases]]
{{Areas of mathematics |collapsed}}
{{Authority control}}


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Latest revision as of 15:19, 19 September 2024

Polynomial equation
Elementary algebra studies which values solve equations formed using arithmetical operations.
Signature of the ring of integers
Abstract algebra studies algebraic structures, such as the ring of integers given by the set of integers together with operations of addition () and multiplication ().

Algebra is the branch of mathematics that studies certain abstract systems, known as algebraic structures, and the manipulation of statements within those systems. It is a generalization of arithmetic that introduces variables and algebraic operations other than the standard arithmetic operations such as addition and multiplication.

Elementary algebra is the main form of algebra taught in school and examines mathematical statements using variables for unspecified values. It seeks to determine for which values the statements are true. To do so, it uses different methods of transforming equations to isolate variables. Linear algebra is a closely related field investigating variables that appear in several linear equations, called a system of linear equations. It tries to discover the values that solve all equations in the system at the same time.

Abstract algebra studies algebraic structures, which consist of a set of mathematical objects together with one or several operations defined on that set. It is a generalization of elementary and linear algebra since it allows mathematical objects other than numbers and non-arithmetic operations. It distinguishes between different types of algebraic structures, such as groups, rings, and fields, based on the number of operations they use and the laws they follow. Universal algebra provides a general framework to investigate abstract patterns that characterize different classes of algebraic structures.

Algebraic methods were first studied in the ancient period to solve specific problems in fields like geometry. Subsequent mathematicians examined general techniques to solve equations independent of their specific applications. They described equations and their solutions using words and abbreviations until the 16th and 17th centuries, when a rigorous symbolic formalism was developed. In the mid-19th century, the scope of algebra broadened beyond a theory of equations to cover diverse types of algebraic operations and structures. Algebra is relevant to many branches of mathematics, such as geometry, topology, number theory, and calculus, and other fields of inquiry, like logic and the empirical sciences.

Definition and etymology

[edit]

Algebra is the branch of mathematics that studies algebraic structures and the operations[a] they use.[2] An algebraic structure is a non-empty set of mathematical objects, such as the real numbers, together with algebraic operations defined on that set, like addition and multiplication.[3] Algebra explores the laws, general characteristics, and types of algebraic structures. Within certain algebraic structures, it examines the use of variables in equations and how to manipulate these equations.[4][b]

Algebra is often understood as a generalization of arithmetic.[8] Arithmetic studies operations like addition, subtraction, multiplication, and division, in a particular domain of numbers, such as the real numbers.[9] Elementary algebra constitutes the first level of abstraction. Like arithmetic, it restricts itself to specific types of numbers and operations. It generalizes these operations by allowing indefinite quantities in the form of variables in addition to numbers.[10] A higher level of abstraction is found in abstract algebra, which is not limited to a particular domain and examines algebraic structures such as groups and rings. It extends beyond typical arithmetic operations by also covering other types of operations.[11] Universal algebra is still more abstract in that it is not interested in specific algebraic structures but investigates the characteristics of algebraic structures in general.[12]

Title page of The Compendious Book on Calculation by Completion and Balancing
The word algebra comes from the title of al-Khwarizmi's book Al-Jabr.[13]

The term "algebra" is sometimes used in a more narrow sense to refer only to elementary algebra or only to abstract algebra.[14] When used as a countable noun, an algebra is a specific type of algebraic structure that involves a vector space equipped with a certain type of binary operation.[15] Depending on the context, "algebra" can also refer to other algebraic structures, like a Lie algebra or an associative algebra.[16]

The word algebra comes from the Arabic term الجبر (al-jabr), which originally referred to the surgical treatment of bonesetting. In the 9th century, the term received a mathematical meaning when the Persian mathematician Muhammad ibn Musa al-Khwarizmi employed it to describe a method of solving equations and used it in the title of a treatise on algebra, al-Kitāb al-Mukhtaṣar fī Ḥisāb al-Jabr wal-Muqābalah [The Compendious Book on Calculation by Completion and Balancing] which was translated into Latin as Liber Algebrae et Almucabola.[c] The word entered the English language in the 16th century from Italian, Spanish, and medieval Latin.[18] Initially, its meaning was restricted to the theory of equations, that is, to the art of manipulating polynomial equations in view of solving them. This changed in the 19th century[d] when the scope of algebra broadened to cover the study of diverse types of algebraic operations and structures together with their underlying axioms, the laws they follow.[21]

Major branches

[edit]

Elementary algebra

[edit]
Diagram of an algebraic expression
Algebraic expression notation:
  1 – power (exponent)
  2 – coefficient
  3 – term
  4 – operator
  5 – constant term
  – constant
  – variables

Elementary algebra, also called school algebra, college algebra, and classical algebra,[22] is the oldest and most basic form of algebra. It is a generalization of arithmetic that relies on variables and examines how mathematical statements may be transformed.[23]

Arithmetic is the study of numerical operations and investigates how numbers are combined and transformed using the arithmetic operations of addition, subtraction, multiplication, division, exponentiation, extraction of roots, and logarithm. For example, the operation of addition combines two numbers, called the addends, into a third number, called the sum, as in .[9]

Elementary algebra relies on the same operations while allowing variables in addition to regular numbers. Variables are symbols for unspecified or unknown quantities. They make it possible to state relationships for which one does not know the exact values and to express general laws that are true, independent of which numbers are used. For example, the equation belongs to arithmetic and expresses an equality only for these specific numbers. By replacing the numbers with variables, it is possible to express a general law that applies to any possible combination of numbers, like the commutative property of multiplication, which is expressed in the equation .[23]

Algebraic expressions are formed by using arithmetic operations to combine variables and numbers. By convention, the lowercase letters , , and represent variables. In some cases, subscripts are added to distinguish variables, as in , , and . The lowercase letters , , and are usually used for constants and coefficients.[e] The expression is an algebraic expression created by multiplying the number 5 with the variable and adding the number 3 to the result. Other examples of algebraic expressions are and .[25]

Some algebraic expressions take the form of statements that relate two expressions to one another. An equation is a statement formed by comparing two expressions, saying that they are equal. This can be expressed using the equals sign (), as in . Inequations involve a different type of comparison, saying that the two sides are different. This can be expressed using symbols such as the less-than sign (), the greater-than sign (), and the inequality sign (). Unlike other expressions, statements can be true or false and their truth value usually depends on the values of the variables. For example, the statement is true if is either 2 or −2 and false otherwise.[26] Equations with variables can be divided into identity equations and conditional equations. Identity equations are true for all values that can be assigned to the variables, such as the equation . Conditional equations are only true for some values. For example, the equation is only true if is 5.[27]

The main goal of elementary algebra is to determine the values for which a statement is true. This can be achieved by transforming and manipulating statements according to certain rules. A key principle guiding this process is that whatever operation is applied to one side of an equation also needs to be done to the other side. For example, if one subtracts 5 from the left side of an equation one also needs to subtract 5 from the right side to balance both sides. The goal of these steps is usually to isolate the variable one is interested in on one side, a process known as solving the equation for that variable. For example, the equation can be solved for by adding 7 to both sides, which isolates on the left side and results in the equation .[28]

There are many other techniques used to solve equations. Simplification is employed to replace a complicated expression with an equivalent simpler one. For example, the expression can be replaced with the expression since by the distributive property.[29] Factorization is used to rewrite an expression as a product of several factors. This technique is commonly used to determine the values of a polynomial[f] that evaluate to zero. For example, the polynomial can be factorized as . The polynomial as a whole is zero if and only if one of its factors is zero, i.e., if is either −2 or 5.[31] For statements with several variables, substitution is a common technique to replace one variable with an equivalent expression that does not use this variable. For example, if one knows that then one can simplify the expression to arrive at . In a similar way, if one knows the value of one variable one may be able to use it to determine the value of other variables.[32]

Graph of equation "y = 0.5x - 1"
Algebraic equations can be used to describe geometric figures. All values for and that solve the equation are interpreted as points. They are drawn as a red, upward-sloping line in the graph above.

Algebraic equations can be interpreted geometrically to describe spatial figures in the form of a graph. To do so, the different variables in the equation are understood as coordinates and the values that solve the equation are interpreted as points of a graph. For example, if is set to zero in the equation , then must be −1 for the equation to be true. This means that the -pair is part of the graph of the equation. The -pair , by contrast, does not solve the equation and is therefore not part of the graph. The graph encompasses the totality of -pairs that solve the equation.[33]

Linear algebra

[edit]

Linear algebra employs the methods of elementary algebra to study systems of linear equations.[34][g] An equation is linear if it can be expressed in the form where , , ..., and are constants. This means that no variables are multiplied with each other and no variables are raised to a power greater than one. For example, the equations and are linear while the equations and are non-linear. Several equations form a system of equations if they all rely on the same set of variables.[36]

Systems of linear equations are often expressed through matrices[h] and vectors[i] to represent the whole system in a single equation. This can be done by moving the variables to the left side of each equation and moving the constant terms to the right side. The system is then expressed by formulating a matrix that contains all the coefficients of the equations and multiplying it with the column vector made up of the variables.[39] For example, the system of equations can be written as

Like elementary algebra, linear algebra is interested in manipulating and transforming equations to solve them. It goes beyond elementary algebra by dealing with several equations at once and looking for the values for which all equations are true at the same time. For example, if the system is made of the two equations and then using the values 1 and 3 for and does not solve the system of equations because it only solves the first but not the second equation.[40]

Two central questions in linear algebra are whether a system of equations has any solutions and, if so, whether it has a unique solution. A system of equations has no solutions if it is inconsistent, meaning that two or more equations contradict each other. For example, the equations and contradict each other since no values of and exist that solve both equations at the same time. Only consistent systems of equations have solutions.[41]

Whether a consistent system of equations has a unique solution depends on the number of variables and independent equations. Several equations are independent of each other if they do not provide the same information and cannot be derived from each other. A unique solution exists if the number of variables is the same as the number of independent equations. Underdetermined systems, by contrast, have more variables than independent equations and have an infinite number of solutions if they are consistent.[42]

Graph of two linear equations
Linear equations with two variables can be interpreted geometrically as lines. The solution of a system of linear equations is where the lines intersect.

Many techniques employed in elementary algebra to solve equations are also applied in linear algebra. The substitution method starts with one equation and isolates one variable in it. It proceeds to the next equation and replaces the isolated variable with the found expression, thereby reducing the number of unknown variables by one. It applies the same process again to this and the remaining equations until the values of all variables are determined.[43] The elimination method creates a new equation by adding one equation to another equation. This way, it is possible to eliminate one variable that appears in both equations. For a system that contains the equations and , it is possible to eliminate by adding the first to the second equation, thereby revealing that is 13. In some cases, the equation has to be multiplied by a constant before adding it to another equation.[44] Many advanced techniques implement algorithms based on matrix calculations, such as Cramer's rule, the Gauss–Jordan elimination, and LU decomposition.[45]

Systems of equations can be interpreted as geometric figures. For systems with two variables, each equation represents a line in two-dimensional space. The point where the two lines intersect is the solution of the full system because this is the only point that solves both the first and the second equation. For inconsistent systems, the two lines run parallel, meaning that there is no solution since they never intersect. If two equations are not independent then they describe the same line, meaning that every solution of one equation is also a solution of the other equation. These relations make it possible to seek solutions graphically by plotting the equations and determining where they intersect.[46] The same principles also apply to systems of equations with more variables, with the difference being that the equations do not describe lines but higher dimensional figures. For instance, equations with three variables correspond to planes in three-dimensional space, and the points where all planes intersect solve the system of equations.[47]

Abstract algebra

[edit]

Abstract algebra, also called modern algebra,[48] studies different types of algebraic structures. An algebraic structure is a framework for understanding operations on mathematical objects, like the addition of numbers. While elementary algebra and linear algebra work within the confines of particular algebraic structures, abstract algebra takes a more general approach that compares how algebraic structures differ from each other and what types of algebraic structures there are, such as groups, rings, and fields.[49] The key difference between these types of algebraic structures lies in the number of operations they use and the laws they obey.[50]

Diagram of binary operation
Many algebraic structures rely on binary operations, which take two objects as their input and combine them into a single object as output, like addition and multiplication do.

On a formal level, an algebraic structure is a set[j] of mathematical objects, called the underlying set, together with one or several operations.[k] Abstract algebra is primarily interested in binary operations,[l] which take any two objects from the underlying set as inputs and map them to another object from this set as output.[54] For example, the algebraic structure has the natural numbers () as the underlying set and addition () as its binary operation.[52] The underlying set can contain mathematical objects other than numbers and the operations are not restricted to regular arithmetic operations.[55] For instance, the underlying set of the symmetry group of a geometric object is made up of geometric transformations, such as rotations, under which the object remains unchanged. Its binary operation is function composition, which takes two transformations as input and has the transformation resulting from applying the first transformation followed by the second as its output.[56]

Abstract algebra classifies algebraic structures based on the laws or axioms that its operations obey and the number of operations it uses. One of the most basic types is a group, which has one operation and requires that this operation is associative and has an identity element and inverse elements. An operation is associative if the order of several applications does not matter, i.e., if [m] is the same as for all elements. An operation has an identity element or a neutral element if one element e exists that does not change the value of any other element, i.e., if . An operation has inverse elements if for any element there exists a reciprocal element that undoes . If an element operates on its inverse then the result is the neutral element e, expressed formally as . Every algebraic structure that fulfills these requirements is a group.[58] For example, is a group formed by the set of integers together with the operation of addition. The neutral element is 0 and the inverse element of any number is .[59] The natural numbers with addition, by contrast, do not form a group since they contain only positive integers and therefore lack inverse elements.[60] Group theory is the subdiscipline of abstract algebra which studies groups.[61]

A ring is an algebraic structure with two operations ( and ) that work similarly to addition and multiplication. All the requirements of groups also apply to the first operation: it is associative and has an identity element and inverse elements. Additionally, it is commutative, meaning that is true for all elements. The axiom of distributivity governs how the two operations interact with each other. It states that and .[62] The ring of integers is the ring denoted by .[63][n] A ring becomes a field if both operations follow the axioms of associativity, commutativity, and distributivity and if both operations have an identity element and inverse elements.[65][o] The ring of integers does not form a field because it lacks multiplicative inverses. For example, the multiplicative inverse of is , which is not part of the integers. The rational numbers, the real numbers, and the complex numbers each form a field with the operations addition and multiplication.[67]

Diagram of relations between some algebraic structures
Diagram of relations between some algebraic structures. For instance, its top right section shows that a magma becomes a semigroup if its operation is associative.

Besides groups, rings, and fields, there are many other algebraic structures studied by abstract algebra. They include magmas, semigroups, monoids, abelian groups, commutative rings, modules, lattices, vector spaces, and algebras over a field. They differ from each other in regard to the types of objects they describe and the requirements that their operations fulfill. Many are related to each other in that a basic structure can be turned into a more advanced structure by adding additional requirements.[50] For example, a magma becomes a semigroup if its operation is associative.[68]

Universal algebra

[edit]

Universal algebra is the study of algebraic structures in general. As part of its general perspective, it is not concerned with the specific elements that make up the underlying sets and considers operations with more than two inputs, such as ternary operations. It provides a framework for investigating what structural features different algebraic structures have in common.[69][p] One of those structural features concerns the identities that are true in different algebraic structures. In this context, an identity is a universal equation or an equation that is true for all elements of the underlying set. For example, commutativity is a universal equation that states that is identical to for all elements.[71] Two algebraic structures that share all their identities are said to belong to the same variety.[72] For instance, the ring of integers and the ring of polynomials form part of the same variety because they have the same identities, like commutativity and associativity. The field of rational numbers, by contrast, does not belong to this variety since it has additional identities, such as the existence of multiplicative inverses.[73][r]

Homomorphisms are tools in universal algebra to examine structural features by comparing two algebraic structures.[76] A homomorphism is a function from the underlying set of one algebraic structure to the underlying set of another algebraic structure that preserves certain structural characteristics. If the two algebraic structures use binary operations and have the form and then the function is a homomorphism if it fulfills the following requirement: . The existence of a homomorphism reveals that the operation in the second algebraic structure plays the same role as the operation does in the first algebraic structure.[77] Isomorphisms are a special type of homomorphism that indicates a high degree of similarity between two algebraic structures. An isomorphism is a bijective homomorphism, meaning that it establishes a one-to-one relationship between the elements of the two algebraic structures. This implies that every element of the first algebraic structure is mapped to one unique element in the second structure without any unmapped elements in the second structure.[78]

Venn diagram of a set and its subset
Subalgebras restrict their operations to a subset of the underlying set of the original algebraic structure.

Another tool of comparison is the relation between an algebraic structure and its subalgebra.[79] The algebraic structure and its subalgebra use the same operations,[s] which follow the same axioms. The only difference is that the underlying set of the subalgebra is a subset of the underlying set of the algebraic structure.[t] All operations in the subalgebra are required to be closed in its underlying set, meaning that they only produce elements that belong to this set.[79] For example, the set of even integers together with addition is a subalgebra of the full set of integers together with addition. This is the case because the sum of two even numbers is again an even number. But the set of odd integers together with addition is not a subalgebra because it is not closed: adding two odd numbers produces an even number, which is not part of the chosen subset.[80]

History

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Rhind Papyrus
The Rhind Mathematical Papyrus from ancient Egypt, dated c. 1650 BCE, is one of the earliest documents discussing algebraic problems.

The origin of algebra lies in attempts to solve mathematical problems involving arithmetic calculations and unknown quantities. These developments happened in the ancient period in Babylonia, Egypt, Greece, China, and India. One of the earliest documents on algebraic problems is the Rhind Mathematical Papyrus from ancient Egypt, which was written around 1650 BCE.[u] It discusses solutions to linear equations, as expressed in problems like "A quantity; its fourth is added to it. It becomes fifteen. What is the quantity?" Babylonian clay tablets from around the same time explain methods to solve linear and quadratic polynomial equations, such as the method of completing the square.[83]

Many of these insights found their way to the ancient Greeks. Starting in the 6th century BCE, their main interest was geometry rather than algebra, but they employed algebraic methods to solve geometric problems. For example, they studied geometric figures while taking their lengths and areas as unknown quantities to be determined, as exemplified in Pythagoras' formulation of the difference of two squares method and later in Euclid's Elements.[84] In the 3rd century CE, Diophantus provided a detailed treatment of how to solve algebraic equations in a series of books called Arithmetica. He was the first to experiment with symbolic notation to express polynomials.[85] In ancient China, The Nine Chapters on the Mathematical Art, a book composed over the period spanning from the 10th century BCE to the 2nd century CE,[86] explored various techniques for solving algebraic equations, including the use of matrix-like constructs.[87]

It is controversial to what extent these early developments should be considered part of algebra proper rather than precursors. They offered solutions to algebraic problems but did not conceive them in an abstract and general manner, focusing instead on specific cases and applications.[88] This changed with the Persian mathematician al-Khwarizmi,[v] who published his The Compendious Book on Calculation by Completion and Balancing in 825 CE. It presents the first detailed treatment of general methods that can be used to manipulate linear and quadratic equations by "reducing" and "balancing" both sides.[90] Other influential contributions to algebra came from the Arab mathematician Thābit ibn Qurra also in the 9th century and the Persian mathematician Omar Khayyam in the 11th and 12th centuries.[91]

In India, Brahmagupta investigated how to solve quadratic equations and systems of equations with several variables in the 7th century CE. Among his innovations were the use of zero and negative numbers in algebraic equations.[92] The Indian mathematicians Mahāvīra in the 9th century and Bhāskara II in the 12th century further refined Brahmagupta's methods and concepts.[93] In 1247, the Chinese mathematician Qin Jiushao wrote the Mathematical Treatise in Nine Sections, which includes an algorithm for the numerical evaluation of polynomials, including polynomials of higher degrees.[94]

Drawing of François Viète
Painting of René Descartes
François Viète (left) and René Descartes invented a symbolic notation to express equations in an abstract and concise manner.

The Italian mathematician Fibonacci brought al-Khwarizmi's ideas and techniques to Europe in books including his Liber Abaci.[95] In 1545, the Italian polymath Gerolamo Cardano published his book Ars Magna, which covered many topics in algebra, discussed imaginary numbers, and was the first to present general methods for solving cubic and quartic equations.[96] In the 16th and 17th centuries, the French mathematicians François Viète and René Descartes introduced letters and symbols to denote variables and operations, making it possible to express equations in an abstract and concise manner. Their predecessors had relied on verbal descriptions of problems and solutions.[97] Some historians see this development as a key turning point in the history of algebra and consider what came before it as the prehistory of algebra because it lacked the abstract nature based on symbolic manipulation.[98]

Photo of Garrett Birkhoff
Garrett Birkhoff developed many of the foundational concepts of universal algebra.

Many attempts in the 17th and 18th centuries to find general solutions[w] to polynomials of degree five and higher failed.[100] At the end of the 18th century, the German mathematician Carl Friedrich Gauss proved the fundamental theorem of algebra, which describes the existence of zeros of polynomials of any degree without providing a general solution.[19] At the beginning of the 19th century, the Italian mathematician Paolo Ruffini and the Norwegian mathematician Niels Henrik Abel were able to show that no general solution exists for polynomials of degree five and higher.[100] In response to and shortly after their findings, the French mathematician Évariste Galois developed what came later to be known as Galois theory, which offered a more in-depth analysis of the solutions of polynomials while also laying the foundation of group theory.[20] Mathematicians soon realized the relevance of group theory to other fields and applied it to disciplines like geometry and number theory.[101]

Starting in the mid-19th century, interest in algebra shifted from the study of polynomials associated with elementary algebra towards a more general inquiry into algebraic structures, marking the emergence of abstract algebra. This approach explored the axiomatic basis of arbitrary algebraic operations.[102] The invention of new algebraic systems based on different operations and elements accompanied this development, such as Boolean algebra, vector algebra, and matrix algebra.[103] Influential early developments in abstract algebra were made by the German mathematicians David Hilbert, Ernst Steinitz, and Emmy Noether as well as the Austrian mathematician Emil Artin. They researched different forms of algebraic structures and categorized them based on their underlying axioms into types, like groups, rings, and fields.[104] The idea of the even more general approach associated with universal algebra was conceived by the English mathematician Alfred North Whitehead in his 1898 book A Treatise on Universal Algebra. Starting in the 1930s, the American mathematician Garrett Birkhoff expanded these ideas and developed many of the foundational concepts of this field.[105] Closely related developments were the formulation of model theory, category theory, topological algebra, homological algebra, Lie algebras, free algebras, and homology groups.[106]

Applications

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The influence of algebra is wide-reaching and includes many branches of mathematics as well as the empirical sciences. Algebraic notation and principles play a key role in physics and related disciplines to express scientific laws and solve equations.[107] They are also used in fields like engineering, economics, computer science, and geography to express relationships, solve problems, and model systems.[108]

Other branches of mathematics

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The algebraization of mathematics is the process of applying algebraic methods and principles to other branches of mathematics. It happens by employing symbols in the form of variables to express mathematical insights on a more general level, allowing mathematicians to develop formal models describing how objects interact and relate to each other.[109] This is possible because the abstract patterns studied by algebra have many concrete applications in fields such as geometry, topology, number theory, and calculus.[110]

Rendered image of a sphere
The algebraic equation describes a sphere at the origin with a radius of 1.

Geometry is interested in geometric figures, which can be described with algebraic statements. For example, the equation describes a line in two-dimensional space while the equation corresponds to a sphere in three-dimensional space. Of special interest to algebraic geometry are algebraic varieties,[x] which are solutions to systems of polynomial equations that can be used to describe more complex geometric figures.[112] Algebraic reasoning can also solve geometric problems. For example, one can determine whether and where the line described by intersects with the circle described by by solving the system of equations made up of these two equations.[113] Topology studies the properties of geometric figures or topological spaces that are preserved under operations of continuous deformation. Algebraic topology relies on algebraic theories such as group theory to classify topological spaces. For example, homotopy groups classify topological spaces based on the existence of loops or holes in them.[114] Number theory is concerned with the properties of and relations between integers. Algebraic number theory applies algebraic methods and principles to this field of inquiry. Number theorists employ algebraic expressions to describe general laws, like Fermat's Last Theorem, and analyze how numbers form algebraic structures, such as the ring of integers.[115] The insights of algebra are also relevant to calculus, which utilizes mathematical expressions to examine rates of change and accumulation. It relies on algebra to understand how these expressions can be transformed and what role variables play in them.[116]

Picture of Rubik's cube
The faces of a Rubik's cube can be rotated to change the arrangement of colored patches. The resulting permutations form a group called the Rubik's Cube group.[117]

Abstract algebra has various uses in applied mathematics, ranging from electronics and robotics to cryptography.[118] More specific applications are the use of group theory to solve puzzles including Sudoku and Rubik's cubes[119] and the reliance on algebraic tools to analyze origami.[120]

Logic

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Logic is the study of correct reasoning.[121] Algebraic logic employs algebraic methods to describe and analyze the structures and patterns that underlie logical reasoning.[122] One part of it is interested in understanding the mathematical structures themselves without regard for the concrete consequences they have on the activity of drawing inferences. Another part investigates how the problems of logic can be expressed in the language of algebra and how the insights obtained through algebraic analysis affect logic.[123]

Boolean algebra is an influential device in algebraic logic to describe propositional logic.[124] Propositions are statements that can be true or false.[125] Propositional logic uses logical connectives to combine two propositions to form a complex proposition. For example, the connective "if ... then" can be used to combine the propositions "it rains" and "the streets are wet" to form the complex proposition "if it rains then the streets are wet". Propositional logic is interested in how the truth value of a complex proposition depends on the truth values of its constituents.[126] With Boolean algebra, this problem can be addressed by interpreting truth values as numbers: 0 corresponds to false and 1 corresponds to true. Logical connectives are understood as binary operations that take two numbers as input and return the output that corresponds to the truth value of the complex proposition.[127] Algebraic logic is also interested in how more complex systems of logic can be described through algebraic structures and which varieties and quasivarities these algebraic structures belong to.[128]

Education

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Diagram of a balance scale
Balance scales are used in algebra education to help students understand how equations can be transformed to determine unknown values.[129]

Algebra education mostly focuses on elementary algebra, which is one of the reasons why elementary algebra is also called school algebra. It is usually not introduced until secondary education since it requires mastery of the fundamentals of arithmetic while posing new cognitive challenges associated with abstract reasoning and generalization.[130] It aims to familiarize students with the formal side of mathematics by helping them understand mathematical symbolism, for example, how variables can be used to represent unknown quantities. An additional difficulty for students lies in the fact that, unlike arithmetic calculations, algebraic expressions are often difficult to solve directly. Instead, students need to learn how to transform them according to certain laws, often with the goal of determining an unknown quantity.[131]

Some tools to introduce students to the abstract side of algebra rely on concrete models and visualizations of equations, including geometric analogies, manipulatives including sticks or cups, and "function machines" representing equations as flow diagrams. One method uses balance scales as a pictorial approach to help students grasp basic problems of algebra. The mass of some objects on the scale is unknown and represents variables. Solving an equation corresponds to adding and removing objects on both sides in such a way that the sides stay in balance until the only object remaining on one side is the object of unknown mass.[132] Word problems are another tool to show how algebra is applied to real-life situations. For example, students may be presented with a situation in which Naomi's brother has twice as many apples as Naomi. Given that both together have twelve apples, students are then asked to find an algebraic equation that describes this situation () and to determine how many apples Naomi has ().[133]

See also

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References

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Notes

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  1. ^ When understood in the widest sense, an algebraic operation is a function from a Cartesian power of a set into that set, expressed formally as . Addition of real numbers is an example of an algebraic operation: it takes two numbers as input and produces one number as output. It has the form .[1]
  2. ^ Algebra is covered by division 512 in the Dewey Decimal Classification[5] and subclass QA 150-272.5 in the Library of Congress Classification.[6] It encompasses several areas in the Mathematics Subject Classification.[7]
  3. ^ The exact meaning of the term al-jabr in al-Khwarizmi's work is disputed. In some passages, it expresses that a quantity diminished by subtraction is restored to its original value, similar to how a bonesetter restores broken bones by bringing them into proper alignment.[17]
  4. ^ These changes were in part triggered by discoveries that solved many of the older problems of algebra. For example, the proof of the fundamental theorem of algebra demonstrated the existence of complex solutions of polynomials[19] and the introduction of Galois theory characterized the polynomials that have general solutions.[20]
  5. ^ Constants represent fixed magnitudes that, unlike variables, cannot change.[24]
  6. ^ A polynomial is an expression consisting of one or more terms that are added or subtracted from each other. Each term is either a constant, a variable, or a product of a constant and variables. Each variable can be raised to a positive-integer power. Examples are and .[30]
  7. ^ Another approach defines linear algebra as the study of linear maps between finite-dimensional vector spaces. A linear map is a function that transforms vectors from one vector space to another while preserving the operations of vector addition and scalar multiplication. Linear maps can be used to represent, analyze, and solve systems of linear equations.[35]
  8. ^ A matrix is a table of numbers,[37] such as
  9. ^ A vector is an array of numbers or a matrix with only one column,[38] such as
  10. ^ A set is an unordered collection of distinct elements, such as numbers, vectors, or other sets. Set theory describes the laws and properties of sets.[51]
  11. ^ According to some definitions, algebraic structures include a distinguished element as an additional component, such as the identity element in the case of multiplication.[52]
  12. ^ Some of the algebraic structures studied by abstract algebra include unary operations in addition to binary operations. For example, normed vector spaces have a norm, which is a unary operation often used to associate a vector with its length.[53]
  13. ^ The symbols and are used in this article to represent any operation that may or may not resemble arithmetic operations.[57]
  14. ^ Some definitions additionally require that the second operation is associative.[64]
  15. ^ For the second operation, there is usually one element, corresponding to 0, that does not require an inverse element.[66]
  16. ^ A slightly different approach understands universal algebra as the study of one type of algebraic structures known as universal algebras. Universal algebras are defined in a general manner to include most other algebraic structures. For example, groups and rings are special types of universal algebras.[70]
  17. ^ The conditions take the form of a Horn clause.[74]
  18. ^ Besides identities, universal algebra is also interested in structural features associated with quasi-identities. A quasi-identity is an identity that only needs to be present under certain conditions.[q] It is a generalization of identity in the sense that every identity is a quasi-identity but not every quasi-identity is an identity. Algebraic structures that share all their quasi-identities have certain structural characteristics in common, which is expressed by stating that they belong to the same quasivariety.[75]
  19. ^ According to some definitions, it is also possible for a subalgebra to have fewer operations.[80]
  20. ^ This means that all the elements of the first set are also elements of the second set but the second set may contain elements not found in the first set.[81]
  21. ^ The exact date is disputed and some historians suggest a later date around 1550 BCE.[82]
  22. ^ Some historians consider him the "father of algebra" while others reserve this title for Diophantus.[89]
  23. ^ A general solution or a solution in radicals is a closed-form algebraic equation that isolates the variable on one side. For example, the general solution to quadratic equations of the form is described by the quadratic formula The absence of general solutions does not mean that there are no numerical solutions.[99]
  24. ^ Algebraic varieties studied in geometry differ from the more general varieties studied in universal algebra.[111]

Citations

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  1. ^ Baranovich 2023, Lead section
  2. ^
  3. ^
  4. ^
    • Pratt 2022, Lead section, § 1. Elementary Algebra, § 2. Abstract Algebra, § 3. Universal Algebra
    • Merzlyakov & Shirshov 2020, § The Subject Matter of Algebra, Its Principal Branches and Its Connection with Other Branches of Mathematics.
  5. ^ Higham 2019, p. 296
  6. ^ Library of Congress, p. 3
  7. ^ zbMATH Open 2024
  8. ^
  9. ^ a b
  10. ^
  11. ^
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  16. ^ EoM Staff 2017
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  19. ^ a b
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  23. ^ a b
  24. ^ Sobolev 2015
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  30. ^ Markushevich 2015
  31. ^
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  35. ^
  36. ^
  37. ^
  38. ^ Mirakhor & Krichene 2014, p. 107
  39. ^
  40. ^
  41. ^
  42. ^
  43. ^
  44. ^
  45. ^
  46. ^
  47. ^
  48. ^
  49. ^
  50. ^ a b
    • Pratt 2022, Lead section, § 2. Abstract Algebra
    • Merzlyakov & Shirshov 2020, The Subject Matter of Algebra, Its Principal Branches and Its Connection with Other Branches of Mathematics.
  51. ^
  52. ^ a b Ovchinnikov 2015, p. 27
  53. ^ Grillet 2007, p. 247
  54. ^
  55. ^
  56. ^
  57. ^ Gilbert & Nicholson 2004, p. 4
  58. ^
  59. ^
  60. ^
  61. ^ Tanton 2005, p. 242
  62. ^
  63. ^ Smith 2015, p. 161
  64. ^ Weisstein 2003, p. 2579
  65. ^
  66. ^ Weisstein 2003, p. 1047
  67. ^
  68. ^ Cooper 2011, p. 60
  69. ^
  70. ^
  71. ^
  72. ^
  73. ^
  74. ^ Mal’cev 1973, p. 211
  75. ^
  76. ^
  77. ^
  78. ^
  79. ^ a b
  80. ^ a b Indurkhya 2013, pp. 217–218
  81. ^ Efimov 2014
  82. ^
  83. ^
  84. ^
  85. ^
  86. ^ Burgin 2022, p. 10
  87. ^ Higgins 2015, p. 89
  88. ^
  89. ^
  90. ^
  91. ^
  92. ^
  93. ^
  94. ^
  95. ^
  96. ^
  97. ^
  98. ^
  99. ^
  100. ^ a b
  101. ^
  102. ^
  103. ^
  104. ^
  105. ^
  106. ^
  107. ^
  108. ^
  109. ^
  110. ^
  111. ^
  112. ^
  113. ^ Vince 2007, p. 133
  114. ^
  115. ^
  116. ^
  117. ^ Joyner 2008, p. 92
  118. ^
  119. ^ Terras 2019, pp. 63–64, 142
  120. ^ Hull 2021, pp. 5, 48
  121. ^ Hintikka 2019, Lead section, § Nature and Varieties of Logic
  122. ^
  123. ^ Andréka, Németi & Sain 2001, pp. 133–134
  124. ^
  125. ^ McGrath & Frank 2023, Lead section
  126. ^
  127. ^
  128. ^
  129. ^
  130. ^
  131. ^
  132. ^
  133. ^

Sources

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