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Abstract algebra

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Abstract algebra, often called modern algebra, is the study of algebraic structures. These structures are sets of elements that follow specific rules called operations. While elementary algebra uses variables to solve for unknown numbers, abstract algebra focuses on the underlying patterns of the operations themselves. This field investigates how different sets behave when you combine their members. Common structures include groups, rings, fields, modules, vector spaces, and lattices. By studying these structures, mathematicians can find universal truths that apply to many different areas of science and math.

To understand these structures, one must look at the mechanics of their operations. A structure requires a set and at least one operation that acts on the elements. For example, a group is a set with a single operation that must follow specific laws. One law is closure, meaning the result of the operation stays within the set. Another is associativity, where the grouping of operations does not change the result. Some structures, like rings, use two operations, such as addition and multiplication. These two operations must interact through rules like the distributive law.

Magma to group2
Magma to group2

Algebraic structures are categorized into several distinct types based on their rules. Groups are the most basic, often used to study symmetry, such as the permutations of a Rubik's Cube.

Rubik's cube v2
Rubik's cube v2

Rings are more complex and involve two operations, like the integers where you can add and multiply. Fields are a special kind of ring where you can also perform division. Other structures include vector spaces, which are used to describe directions and magnitudes, and lattices, which deal with order. Each type is defined by which specific axioms, or fundamental rules, it must satisfy.

The history of algebra shows a slow shift from words to symbols to abstraction. Around 1700 BC, Babylonians solved quadratic equations using rhetorical algebra, which relied on written word problems. In 830 AD, Al-Khwarizmi originated the term "algebra," though his work remained rhetorical. Symbolic algebra began to emerge with François Viète in 1591 and René Descartes in 1637. By 1830, George Peacock attempted to establish algebra on a strictly symbolic basis. He argued that symbolical algebra was distinct from arithmetical algebra because its rules could apply without the restrictions of real numbers.

Many mathematicians contributed to the development of group theory during the nineteenth century. In 1832, Évariste Galois was the first to use the term "group" to describe a collection of permutations. Arthur Cayley expanded this in 1854 by defining a group using an associative operation and an identity element. Later, Walther von Dyck became the first to require inverse elements in the definition of a group in 1882. Other major figures included Otto Hölder, who defined quotient groups and automorphisms, and Ferdinand Georg Frobenius, who worked on representation theory. These individual discoveries eventually merged into a unified theory.

Ring theory grew from the study of complex number systems and polynomials. In 1843, William Rowan Hamilton discovered quaternions, which were an extension of complex numbers. This led to the study of noncommutative rings, where the order of multiplication matters. In the 1870s, Benjamin Peirce classified many hypercomplex number systems and defined associative algebras. Later, mathematicians like Emmy Noether studied algebraic functions and curves, which helped lead to the development of algebraic geometry. By 1914, Abraham Fraenkel provided the first formal axiomatic definition of a ring, combining addition and multiplication into a single framework.

Abstract algebra serves as a bridge between many different mathematical disciplines. It connects number theory, which studies the properties of integers, to geometry through the study of symmetry groups. For example, the Erlangen program by Felix Klein in 1872 used groups to study geometry. Category theory provides an even broader framework, allowing mathematicians to study the similarities between different types of structures. Universal algebra also plays a role by studying the properties of algebraic structures as single objects. This interconnectedness allows a single discovery in algebra to impact many different fields of study.

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File:Rubik's cube v2.svg
Rubik's cube v2.svg
File:Magma to group2.svg
Magma to group2.svg
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