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In mathematics, a finite field or Galois field (so-named in honor of Évariste Galois) is a field that contains a finite number of elements.As with any field, a finite field is a set on which the operations of multiplication, addition, subtraction and division are defined and satisfy certain basic rules.
Apart from the trivial case of a zero-dimensional space over any field, a vector space over a field F has a finite number of elements if and only if F is a finite field and the vector space has a finite dimension. Thus we have F q, the unique finite field (up to isomorphism) with q elements. Here q must be a power of a prime (q = p m with p prime).
This field is called a finite field or Galois field with four elements, and is denoted F 4 or GF(4). [8] The subset consisting of O and I (highlighted in red in the tables at the right) is also a field, known as the binary field F 2 or GF(2) .
This requires the property that the field trace Tr L/K provides a non-degenerate quadratic form over K. This can be guaranteed if the extension is separable ; it is automatically true if K is a perfect field , and hence in the cases where K is finite, or of characteristic zero.
While there is a unique finite field of order p n up to isomorphism, the representation of the field elements depends on the choice of irreducible polynomial. The Conway polynomial is a way of standardizing this choice. The non-zero elements of a finite field F form a cyclic group under multiplication, denoted F *.
By making a modular multiplicative inverse table for the finite field and doing a lookup. By mapping to a composite field where inversion is simpler, and mapping back. By constructing a special integer (in case of a finite field of a prime order) or a special polynomial (in case of a finite field of a non-prime order) and dividing it by a. [7]
In mathematics, particularly computational algebra, Berlekamp's algorithm is a well-known method for factoring polynomials over finite fields (also known as Galois fields). The algorithm consists mainly of matrix reduction and polynomial GCD computations. It was invented by Elwyn Berlekamp in 1967.
The trace form for a finite degree field extension L/K has non-negative signature for any field ordering of K. [8] The converse, that every Witt equivalence class with non-negative signature contains a trace form, is true for algebraic number fields K. [8] If L/K is an inseparable extension, then the trace form is identically 0. [9]