Module

ContinuousH1CupFiniteStage.lean

Nyll.GaloisCohomology.ProP.ContinuousH1CupFiniteStage
1 declaration indexed from sourceView source ↗

Finite-stage realization of the canonical continuous H¹ cup

Two continuous mod-p characters of a pro-p group factor through one common finite p-group quotient. Restriction naturality then identifies their canonical cup with inflation of the cup of the descended characters.

Declarations

ClassFieldTower.Cohomology.exists_finiteStage_continuousH1Cup

Two continuous mod-p characters, and their canonical degree-two cup, descend to one common finite p-group quotient.

Source context 9 commands

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

open scoped Topology
namespace ClassFieldTower.Cohomology
open ProCGroups ProCGroups.ProC
open ClassFieldTower.ProP
noncomputable section
universe u
variable {p : ℕ} [Fact p.Prime]
variable {G : Type u} [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable [CompactSpace G] [T2Space G]
theorem exists_finiteStage_continuousH1Cup
    (hG : HasOpenNormalBasisInClass (FiniteGroupClass.pGroup p) G)
    (χ ψ : ContinuousH1ZMod (p := p) (G := G)) :
    ∃ U : OpenNormalSubgroupInClass (FiniteGroupClass.pGroup p) G,
      ∃ χU ψU : ContinuousH1ZMod
          (p := p) (G := G ⧸ (U.1 : Subgroup G)),
        continuousH1ZModRestriction
            (OpenNormalSubgroupInClass.quotientProj U) χU = χ ∧
          continuousH1ZModRestriction
            (OpenNormalSubgroupInClass.quotientProj U) ψU = ψ ∧
          (continuousCohomologyZModPMapLifted p
              (OpenNormalSubgroupInClass.quotientProj U) 2).hom
              (continuousH1CupProductLifted χU ψU) =
            continuousH1CupProductLifted χ ψ