Absolute Galois group

In mathematics, the absolute Galois group G_K of a field K is the Galois group of K^sep over K, where K^sep is a separable closure of K. Alternatively it is the group of all automorphisms of the algebraic closure of K that fix K. The absolute Galois group is well-defined up to inner automorphism. It is a profinite group.

(When K is a perfect field, K^sep is the same as an algebraic closure K^alg of K. This holds e.g. for K of characteristic zero, or K a finite field.)

(For the notation, see Inverse limit.)

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