Module

AbsoluteGaloisLiftComparison.lean

Nyll.GaloisCohomology.Topology.AbsoluteGaloisLiftComparison
1 declaration indexed from sourceView source ↗

Independence of closure lifts for commutative characters

A closure embedding intertwining two Galois automorphisms identifies their values under every continuous character with commutative target. Its difference from mathlib's chosen lift is removed by an inner automorphism.

Declarations

Field.absoluteGaloisGroup.character_map_apply_of_lift

Any compatible closure embedding computes the same commutative character restriction as the chosen absolute Galois map.

Source context 2 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace Field.absoluteGaloisGroup
variable {K L : Type*} [Field K] [Field L]
theorem character_map_apply_of_lift
    {A : Type*} [CommGroup A] [TopologicalSpace A]
    (f : K →+* L) (j : AlgebraicClosure K →+* AlgebraicClosure L)
    (hj : ∀ x : K, j (algebraMap K (AlgebraicClosure K) x) =
      algebraMap L (AlgebraicClosure L) (f x))
    (σ : Gal(AlgebraicClosure L/L)) (θ : Gal(AlgebraicClosure K/K))
    (hθ : ∀ x, j (θ x) = σ (j x))
    (χ : Gal(AlgebraicClosure K/K) →ₜ* A) :
    χ (map f σ) = χ θ