Module

AlgebraicExtensionHenselian.lean

Nyll.ValuedFieldTheory.Valuation.Henselian.AlgebraicExtensionHenselian
1 declaration indexed from sourceView source ↗

Henselianity of algebraic extension valuation rings

Chevalley's theorem supplies an extension over every further algebraic field. Uniqueness over the original Henselian base makes this extension unique. The valuation-ring criterion then supplies Henselianity upstairs.

Declarations

ValuationTheory.Henselian.henselianRing_of_algebraic_extension

An algebraic extension of a Henselian valuation ring is Henselian, without rank, discreteness, completeness, or separability assumptions.

Source context 3 commands

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

namespace ValuationTheory.Henselian
variable {K L : Type*} [Field K] [Field L] [Algebra K L] [Algebra.IsAlgebraic K L]
  (V : ValuationSubring K) [HenselianRing V (IsLocalRing.maximalIdeal V)]
  (W : ValuationSubring L) [V.valuation.HasExtension W.valuation]
include V in
theorem henselianRing_of_algebraic_extension :
    HenselianRing W (IsLocalRing.maximalIdeal W)