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Number Field


If r is an algebraic number of degree n, then the totality of all expressions that can be constructed from r by repeated additions, subtractions, multiplications, and divisions is called a number field (or an algebraic number field) generated by r, and is denoted F[r]. Formally, a number field is a finite extension Q(alpha) of the field Q of rational numbers.

The elements of a number field which are roots of a polynomial

 z^n+a_(n-1)z^(n-1)+...+a_0=0

with integer coefficients and leading coefficient 1 are called the algebraic integers of that field.

The coefficients of an algebraic equations such as the quintic equation can be characterized by the groups of their associated number fields. A database of the groups of number field polynomials is maintained by Klüners and Malle. For example, the polynomial x^5-x^4+2x^3-4x^2+x-1 is associated with the group F(5) of order 20.


See also

Algebraic Integer, Algebraic Number, Field, Finite Field, Function Field, Local Field, Number Field Order, Number Field Sieve, Number Field Signature, Number Ring, Q, Quadratic Field

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References

Cohen, H. A Course in Computational Algebraic Number Theory, 3rd. corr. ed. New York: Springer-Verlag, 1996.Courant, R. and Robbins, H. What Is Mathematics?: An Elementary Approach to Ideas and Methods, 2nd ed. Oxford, England: Oxford University Press, p. 127, 1996.Klüners, J. and Malle, G. "A Database for Number Fields." http://www.mathematik.uni-kassel.de/~klueners/minimum/minimum.html.Shanks, D. Solved and Unsolved Problems in Number Theory, 4th ed. New York: Chelsea, pp. 151-152, 1993.Wolfram, S. A New Kind of Science. Champaign, IL: Wolfram Media, p. 1168, 2002.

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Number Field

Cite this as:

Weisstein, Eric W. "Number Field." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/NumberField.html

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