Module

ActualFiniteRawTameTower.lean

Nyll.EtaleFundamentalGroups.Inertia.ActualFiniteRawTameTower
1 declaration indexed from sourceView source ↗

Raw tame values in finite towers

Proves the power relation between raw coefficient-ratio residues of the same original inertia element at nested finite local normalizations.

Declarations

EtaleFundamentalGroups.Inertia.actualFiniteRawTameValue_tower

The two independently constructed raw values of the SAME original inertia element satisfy the literal finite local tower relation. The ratio witnesses, commuting square, residue fixedness and ambient triangle are all supplied by their original-input owners. No finite inertia action or roots carrier is opened.

Source context 4 commands

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

noncomputable section
namespace EtaleFundamentalGroups.Inertia
open SchemeTheory RamificationTheory.HilbertRamification.DiscreteValuationRing
universe u v w
theorem actualFiniteRawTameValue_tower
    (A : Type u) (K : Type v) (L : Type w)
    [CommRing A] [IsDomain A] [IsDiscreteValuationRing A]
    [Field K] [Field L] [Algebra A K] [IsFractionRing A K]
    [Algebra K L] [Algebra A L] [IsScalarTower A K L] [IsGalois K L]
    (Q : Ideal (normalizationCommAlgCat A L)) [Q.IsMaximal]
    (E F : FiniteGaloisIntermediateField K L) (h : E ≤ F)
    (σ : actualNormalizationInertiaGroup A K L Q) :
    letI := finiteAbsoluteNormalizationPrime_isPrime A K L Q E
    letI := finiteAbsoluteNormalizationPrime_isPrime A K L Q F
    letI := finiteAbsoluteNormalizationAlgebra_isDedekindDomain A K L F
    letI := localizationAtPrime_isDiscreteValuationRing
      (finiteAbsoluteNormalizationAlgebra A K L F)
      (finiteAbsoluteNormalizationPrime A K L Q F)
      (finiteAbsoluteNormalizationPrime_ne_bot A K L Q F)
    ∃ π : Localization.AtPrime (finiteAbsoluteNormalizationPrime A K L Q E),
      Irreducible π ∧
      actualFiniteRawTameValue A K L Q E σ =
        actualFiniteRawTameValue A K L Q F σ ^
          ((IsDiscreteValuationRing.addVal
            (Localization.AtPrime (finiteAbsoluteNormalizationPrime A K L Q F))).toFun
            ((actualFiniteNormalizationTowerLocalRingMap A K L Q E F h).toFun π)).toNat := by
  let pE := finiteAbsoluteNormalizationPrime_isPrime A K L Q E
  let pF := finiteAbsoluteNormalizationPrime_isPrime A K L Q F
  let dF := finiteAbsoluteNormalizationAlgebra_isDedekindDomain A K L F
  let vF := localizationAtPrime_isDiscreteValuationRing
    (finiteAbsoluteNormalizationAlgebra A K L F)
    (finiteAbsoluteNormalizationPrime A K L Q F)
    (finiteAbsoluteNormalizationPrime_ne_bot A K L Q F)
  obtain ⟨π, c, hπ, _, hc, hE⟩ := actualFiniteRawTameValue_exists_coefficient A K L Q E σ
  obtain ⟨ρ, d, hρ, _, hd, hF⟩ := actualFiniteRawTameValue_exists_coefficient A K L Q F σ
  refine ⟨π, hπ, ?_⟩
  have hraw := uniformizerAmbientCoefficient_tower_addVal_of_ringHom
    (Localization.AtPrime (finiteAbsoluteNormalizationPrime A K L Q E))
    (Localization.AtPrime (finiteAbsoluteNormalizationPrime A K L Q F)) Q.ResidueField
    (actualFiniteNormalizationTowerLocalRingMap A K L Q E F h)
    (actualFiniteNormalizationTowerLocalRingMap_injective A K L Q E F h)
    (actualFiniteInertiaLocalRingHom A K L Q E σ)
    (actualFiniteInertiaLocalRingHom A K L Q F σ)
    (actualFiniteInertiaLocalRingHom_tower A K L Q E F h σ)
    (actualFiniteLocalResidueMap A K L Q E) (actualFiniteLocalResidueMap A K L Q F)
    (actualFiniteLocalResidueMap_tower A K L Q E F h)
    (actualFiniteLocalResidueMap_comp_inertia A K L Q F σ)
    π hπ ρ hρ c d hc hd
  exact hE.trans (hraw.trans (congrArg
    (fun z : Q.ResidueField => z ^
      ((IsDiscreteValuationRing.addVal
        (Localization.AtPrime (finiteAbsoluteNormalizationPrime A K L Q F))).toFun
        ((actualFiniteNormalizationTowerLocalRingMap A K L Q E F h).toFun π)).toNat)
    hF.symm))