FieldTheory.exists_moved_DVF_of_fg_posChar
A nontrivial finite-order automorphism of an infinite finitely generated field of positive characteristic moves some discrete valuation class.
Source context 3 commands
Surrounding namespaces, section variables, and local commands at this declaration.
namespace FieldTheory
open ValuationTheory.DiscreteValuationField
universe uLean source · statement
theorem exists_moved_DVF_of_fg_posChar
(K : Type u) [Field K] [Infinite K] (hfg : Field.FG K)
(hchar : ringChar K ≠ 0) (τ : K ≃+* K) (hne : τ ≠ 1)
(n : ℕ) (hn : 0 < n) (hpow : τ ^ n = 1) :
∃ D : DVF.{u,0} K, ¬ D.valuation.IsEquiv (D.valuation.comap τ.toRingHom)