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Hironaka.AnalyticSpace.Glue.Cocycle

The cocycle of three transition data near the real points #

For three normalized transition data P_ij, P_jk, P_ik (Hironaka.AnalyticSpace.Glue.Normalize) between the local complexifications of X | U_i, X | U_j, X | U_k, the two morphisms φ_jk ∘ φ_ij and φ_ik out of the common domain D = Ω_ij ∩ φ_ij⁻¹(Ω_jk) ∩ Ω_ik ⊆ Y_i agree on an open subset N ⊆ D containing f_i(U_i ∩ U_j ∩ U_k): the cocycle condition holds on a neighbourhood of the real points (exists_cocycle_nhd), under the hypothesis huniq that two morphisms out of a neighbourhood of the real points of one complexification into another, both compatible with the structure maps f, agree near the real points; the statement needs it. This is as in the proof of [Car57, §3, Proposition 2], where the set on which the cocycle identity holds is an open set containing the closed subspace. This is exists_eq_near_of_huniq applied to the composite and the direct transition, whose compatibility with f_i, f_k and whose ranges are checked from the fields of the data.

Conventions. The range hypotheses of exists_eq_near_of_huniq (the two morphisms land in Y_k ∖ f_k(U_k ∖ (U_i ∩ U_j ∩ U_k))) hold because the real points of every transition domain lie over its overlap (Ωi_le, Ωj_le of each datum), transitions carry real points to real points (toFun_e_hom_val) and only real points to real points (exists_eq_of_toFun_e_hom_eq). Basic tools come first: composition of the inclusions of open subspaces (restrictOpenIncl_trans), the lift of f restricted to a smaller open subset (complexifyIncl_comp_pairLift), the pulled-back open subset P.pullOpens T ⊆ Y_i of T ⊆ Y_j under the transition (imageOpens of the preimage in the restricted space) and PairIso.mem_of_toFun_eq (real points of the domain lie over V). For U_i ∩ U_j ∩ U_k = ∅, N may be empty; for j = i or k = i with the diagonal datum, the composite is the transition itself and N = D works.

The inclusions of open subspaces compose.

The lift of f ∘ incl_V into Ω, restricted to V' ≤ V, is the lift of f ∘ incl_{V'}.

The preimage of an open subset T ⊆ Y_j under the transition, as an open subset of Y_i.

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    theorem AnalyticSpace.Glue.PairIso.mem_of_toFun_eq {X : AnalyticSpace ℝ} {Ui Uj : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {V : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {hVi : V ≤ Ui} {hVj : V ≤ Uj} (P : PairIso Ci Cj V hVi hVj) (u : ↑↑(X.restrictOpen Ui).toPresheafedSpace) (hu : KLocallyRingedSpace.Hom.toFun Ci.f u ∈ P.Ωi) :
    ↑u ∈ V

    A real point of the domain lies over V.

    Compatibility restricted to a smaller open #

    The lift into D ≤ Ω followed by the inclusion D ≤ Ω is the lift into Ω.

    The cocycle near the real points #

    noncomputable def AnalyticSpace.Glue.tripleDomain {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :

    The common domain Ω_ij ∩ φ_ij⁻¹(Ω_jk) ∩ Ω_ik ⊆ Y_i of the composite and the direct transition.

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      theorem AnalyticSpace.Glue.tripleDomain_le_Ωij {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :
      tripleDomain Pij Pjk Pik ≤ Pij.Ωi
      theorem AnalyticSpace.Glue.tripleDomain_le_Ωik {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :
      tripleDomain Pij Pjk Pik ≤ Pik.Ωi
      theorem AnalyticSpace.Glue.mem_pullOpens_of_mem_tripleDomain {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) {y : ↑↑Ci.Y.toPresheafedSpace} (hy : y ∈ tripleDomain Pij Pjk Pik) :
      noncomputable def AnalyticSpace.Glue.tripleFirst {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :
      Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik) ⟶ Cj.Y.restrictOpen Pjk.Ωi

      The first factor of the composite: D ⟶ Y_j | Ω_jk.

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        noncomputable def AnalyticSpace.Glue.compTrans {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :

        The composite transition φ_jk ∘ φ_ij on the common domain.

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          noncomputable def AnalyticSpace.Glue.directTrans {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :

          The direct transition φ_ik on the common domain.

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            theorem AnalyticSpace.Glue.toFun_tripleFirst_val {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (y : ↑↑(Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik)).toPresheafedSpace) :
            theorem AnalyticSpace.Glue.toFun_directTrans_val {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (y : ↑↑(Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik)).toPresheafedSpace) :
            theorem AnalyticSpace.Glue.toFun_compTrans_val {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (y : ↑↑(Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik)).toPresheafedSpace) :
            theorem AnalyticSpace.Glue.mem_tripleDomain {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (v : ↑↑(X.restrictOpen (Ui ⊓ Uj ⊓ Uk)).toPresheafedSpace) :

            f_i(U_i ∩ U_j ∩ U_k) lies in the common domain.

            theorem AnalyticSpace.Glue.tripleDomain_le_restrictLeOpens {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :
            tripleDomain Pij Pjk Pik ≤ Ci.restrictLeOpens (Ui ⊓ Uj ⊓ Uk)

            The real points of the common domain lie over U_i ∩ U_j ∩ U_k.

            theorem AnalyticSpace.Glue.pairLift_comp_directTrans {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :

            The direct transition is compatible with f_i, f_k on the triple overlap.

            theorem AnalyticSpace.Glue.pairLift_comp_compTrans {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) :

            The composite transition is compatible with f_i, f_k on the triple overlap.

            theorem AnalyticSpace.Glue.toFun_directTrans_mem {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (y : ↑↑(Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik)).toPresheafedSpace) :
            KLocallyRingedSpace.Hom.toFun (directTrans Pij Pjk Pik) y ∈ Ck.restrictLeOpens (Ui ⊓ Uj ⊓ Uk)

            The direct transition sends the common domain into Y_k ∖ f_k(U_k ∖ (U_i ∩ U_j ∩ U_k)).

            theorem AnalyticSpace.Glue.toFun_compTrans_mem {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (y : ↑↑(Ci.Y.restrictOpen (tripleDomain Pij Pjk Pik)).toPresheafedSpace) :
            KLocallyRingedSpace.Hom.toFun (compTrans Pij Pjk Pik) y ∈ Ck.restrictLeOpens (Ui ⊓ Uj ⊓ Uk)

            The composite transition sends the common domain into Y_k ∖ f_k(U_k ∖ (U_i ∩ U_j ∩ U_k)).

            theorem AnalyticSpace.Glue.exists_cocycle_nhd {X : AnalyticSpace ℝ} {Ui Uj Uk : TopologicalSpace.Opens ↑↑X.toPresheafedSpace} {Ci : (X.restrictOpen Ui).Complexification} {Cj : (X.restrictOpen Uj).Complexification} {Ck : (X.restrictOpen Uk).Complexification} (Pij : PairIso Ci Cj (Ui ⊓ Uj) ⋯ ⋯) (Pjk : PairIso Cj Ck (Uj ⊓ Uk) ⋯ ⋯) (Pik : PairIso Ci Ck (Ui ⊓ Uk) ⋯ ⋯) (huniq : ∀ (V : TopologicalSpace.Opens ↑↑X.toPresheafedSpace) (C C' : (X.restrictOpen V).Complexification) (W : TopologicalSpace.Opens ↑↑C.Y.toPresheafedSpace) (hW : ∀ (x : ↑↑(X.restrictOpen V).complexify.toPresheafedSpace), KLocallyRingedSpace.Hom.toFun C.f x ∈ W) (g₁ g₂ : C.Y.restrictOpen W ⟶ C'.Y.toKLocallyRingedSpace), CategoryTheory.CategoryStruct.comp (KLocallyRingedSpace.Hom.restrictTo C.f ⊤ W ⋯) g₁ = CategoryTheory.CategoryStruct.comp ((X.restrictOpen V).complexify.ofRestrict ⊤) C'.f → CategoryTheory.CategoryStruct.comp (KLocallyRingedSpace.Hom.restrictTo C.f ⊤ W ⋯) g₂ = CategoryTheory.CategoryStruct.comp ((X.restrictOpen V).complexify.ofRestrict ⊤) C'.f → ∃ (W₀ : TopologicalSpace.Opens ↑↑C.Y.toPresheafedSpace) (hle : W₀ ≤ W), (∀ (x : ↑↑(X.restrictOpen V).complexify.toPresheafedSpace), KLocallyRingedSpace.Hom.toFun C.f x ∈ W₀) ∧ CategoryTheory.CategoryStruct.comp (C.Y.restrictOpenIncl hle) g₁ = CategoryTheory.CategoryStruct.comp (C.Y.restrictOpenIncl hle) g₂) :

            The cocycle near the real points. Under the uniqueness hypothesis huniq (two morphisms out of a neighbourhood of the real points of one complexification into another, both compatible with the structure maps, agree on a smaller such neighbourhood), the composite φ_jk ∘ φ_ij and the direct φ_ik agree on an open subset N ⊆ D containing f_i(U_i ∩ U_j ∩ U_k).