Module

ConstantExtensionEvaluation.lean

Nyll.AlgebraicCurves.Divisors.ConstantExtensionEvaluation
1 declaration indexed from sourceView source ↗

Evaluation after extension of constants

Sending places to their actual valuation extensions transports divisor evaluation through the coefficient embedding. The comparison follows from residue evaluation, including the negative multiplicities in divisors.

Declarations

AlgebraicCurve.Divisor.evalFun_mapDomain_of_comap

Divisor evaluation commutes with a field embedding and an injective map of places whose valuation rings have the prescribed comap.

Source context 2 commands

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

open scoped BigOperators
namespace AlgebraicCurve.Divisor
theorem evalFun_mapDomain_of_comap
    {K F K' F' : Type*} [Field K] [Field F] [Field K'] [Field F']
    [Algebra K F] [Algebra K' F']
    (τ : K →+* K') (φ : F →+* F')
    (hφ : ∀ a : K, φ (algebraMap K F a) = algebraMap K' F' (τ a))
    (ι : Place K F → Place K' F') (hι : Function.Injective ι)
    (hcomap : ∀ v, (ι v).toValuationSubring.comap φ = v.toValuationSubring)
    (D : Divisor K F) (f : F)
    (hrat : ∀ v ∈ D.support, v.IsRational)
    (hmem : ∀ v ∈ D.support, f ∈ v.toValuationSubring) :
    evalFun (φ f) (Finsupp.mapDomain ι D) = τ (evalFun f D)