Module

ComapResidueCharP.lean

Nyll.ValuedFieldTheory.Valuation.ComapResidueCharP
1 declaration indexed from sourceView source ↗

Residue characteristic under pullback of valuations

The residue-field characteristic of a valuation subring is preserved by pullback along a field embedding. The proof compares natural-number casts with membership in the nonunits.

Declarations

ValuationSubring.charP_residueField_comap

The residue characteristic of the specified valuation subring is preserved by pullback along any field embedding.

Source context 2 commands

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

namespace ValuationSubring
universe u v
theorem charP_residueField_comap
    {K : Type u} {L : Type v} [Field K] [Field L]
    (A : ValuationSubring L) (f : K →+* L) (p : ℕ)
    [CharP (IsLocalRing.ResidueField A) p] :
    CharP (IsLocalRing.ResidueField (A.comap f)) p