A field is a mathematical entity for which addition, substraction, multiplication and division are well-defined.
Please refer to Glossary of field theory for some basic definitions in field theory.
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2 Elementary Introduction 3 Some Useful Theorems 4 Generalisation and related topics |
History
The concept of fields was used implicitly by Abel and Galois on the solvability of equations.
In 1871, Richard Dedekind, called a set of real or complex numbers which is closed under the four arthimetic operations a "field".
In 1881, Leopold Kronecker who defined what he called a "domain of rationality"-which are indeed field of polynomials in modern terms.
In 1893, Heinrich Weber gave the first clear definiton of an abstract field.
Galois, who did not have the term "field" in mind, is honored to be the first mathematician linking group theory and field theory. Galois theory is named after him. However it was Emil Artin who first developed the relationship of groups and fields in great details during 1928-1942.
The central concept of Galois theory is the algebraic extension of an underlying field. It is simply the smallest field containing the underlying field and a root of a polynomial. An algebraically closed field is a field in which every polynomial has a root. For instance, the field of algebraic numbers is the algebraic closure of the field of rational numbers and the field of complex numbers is the algebraic closure of the field of real numbers.
Finite fields are used in coding theory. Again algebraic extension is an important tool.
Binary fields, fields with characteristics 2, are useful in computer science. They are usually studied as an exceptional case in finite field theory because addition and subtraction are the same operation.
Elementary Introduction
The concept of fields was first used to prove that there is no general formula for the roots of real polynomials of degree higher than 4.Some Useful Theorems
Generalisation and related topics
See Ring, Vector space.