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Hironaka.AnalyticSpace.Glue.OverFamily

Closed subspaces and labelled families descend along a gluing over a base #

The resolution of an analytic space comes with its exceptional divisor, a locally finite family of smooth hypersurfaces with simple normal crossings ([Kol07, Definition 24]; [Kol07, Theorem 45, (3)]; [Wlo09, Theorem 2.0.1, (2)]). The sources glue the spaces only: Włodarczyk's Ṽ is "obtained by gluing Ṽ_i along Ṽ_i ∩ Ṽ_j", and the construction "commutes with local analytic isomorphisms" by construction [Wlo09, §4]; Kollár passes from the neighbourhoods of compact sets to their union [Kol07, 44]. That the exceptional families of the pieces glue with the spaces is left to the reader. This module proves the descent step for a gluing datum G : GlueOver X R π dom (Hironaka.AnalyticSpace.Glue.Over):

The label type is arbitrary here. In the resolution of an analytic space the pieces' exceptional families are the traces of one family indexed by the stages of a single run of the resolution functor on the disjoint union of the pieces, so the labelling is the identity (Hironaka.Resolution.Analytic.Kol07Thm45.CoproductGluedFamily), and LabelledCompat comes from the agreement of the stages across the overlaps (CoproductGluedFamilyCompat, ExhaustionChainFamilies, ResolutionOnMembers); the gluing along an exhaustion uses the chain form of Hironaka.Resolution.Analytic.Kol07Thm45.Glue.OverFamilyChain.

noncomputable def AnalyticSpace.GlueOver.restrictGlue {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} (π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace) (dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace) (i j : ι) (Z : (R i).ClosedSubspace) :

The restriction of a closed subspace Z of the i-th piece to the gluing open subset glueOpens i j, as an ideal sheaf of the restricted piece: the pull-back along the open inclusion (the trace on a part).

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    def AnalyticSpace.GlueOver.CompatClosedSubspaces {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) (C : (i : ι) → (R i).ClosedSubspace) :

    Compatibility of closed subspaces of the pieces: on every gluing open subset the transition t i j pulls the j-th subspace back to the i-th.

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      theorem AnalyticSpace.GlueOver.exists_t_eq_of_toFun_ιGlued_eq {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {i j : ι} {y : ↑↑(R i).toPresheafedSpace} {y' : ↑↑(R j).toPresheafedSpace} (h : KLocallyRingedSpace.Hom.toFun (G.ιGlued i) y = KLocallyRingedSpace.Hom.toFun (G.ιGlued j) y') :
      ∃ (x : ↑↑((R i).restrictOpen (glueOpens X R π dom i j)).toPresheafedSpace), ↑x = y ∧ ↑(KLocallyRingedSpace.Hom.toFun (G.t i j) x) = y'

      Two representatives of one glued point are related through the transition (KGlueData.exists_of_ι_base_eq, Mathlib's ι_eq_iff_rel underneath).

      theorem AnalyticSpace.GlueOver.ofRestrict_comp_ιGlued {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (i j : ι) :

      The glue condition of the gluing over X, on the pieces: ofRestrict ≫ ιGlued i and t i j ≫ ofRestrict ≫ ιGlued j agree on the gluing open subset.

      Two stalk-specialization maps along an equality of points compose to the identity.

      The ideal algebra of representative independence: in a commutative square α ≫ a = σ' ≫ β ≫ b with a, b bijective and σ ≫ σ' = 𝟙, ideals I, J with the same image under a, b pull back along α, β to ideals identified by σ.

      noncomputable def AnalyticSpace.GlueOver.pieceStalkIdeal {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (i : ι) (y : ↑↑(R i).toPresheafedSpace) :

      The stalk ideal of the i-th subspace, read on the glued space at the image point.

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        theorem AnalyticSpace.GlueOver.pieceStalkIdeal_eq {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (hc : G.CompatClosedSubspaces C) {i j : ι} {y : ↑↑(R i).toPresheafedSpace} {y' : ↑↑(R j).toPresheafedSpace} (h : KLocallyRingedSpace.Hom.toFun (G.ιGlued i) y = KLocallyRingedSpace.Hom.toFun (G.ιGlued j) y') :

        Representative independence: the piece stalk ideals of two representatives of one glued point agree under the canonical identification of the stalks.

        noncomputable def AnalyticSpace.GlueOver.gluedRep {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (z : ↑↑G.gluedOver.toPresheafedSpace) :
        (i : ι) × ↑↑(R i).toPresheafedSpace

        A representative (i, y) of a point of the glued space.

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          The chosen representative represents: ιGlued (gluedRep z).1 sends (gluedRep z).2 to z.

          noncomputable def AnalyticSpace.GlueOver.gluedStalkIdeal {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (z : ↑↑G.gluedOver.toPresheafedSpace) :

          The glued stalk ideal at z: the piece stalk ideal of a representative, carried to z.

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            theorem AnalyticSpace.GlueOver.gluedStalkIdeal_toFun_ιGlued {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (hc : G.CompatClosedSubspaces C) (i : ι) (y : ↑↑(R i).toPresheafedSpace) :

            The glued stalk ideal at the image of y is the i-th piece stalk ideal.

            A germ of a section transported along an identity of open subsets is the germ of the section.

            The glued stalk ideals have local generators: a piece's generators near the representative, carried to the glued space through the open immersion's invApp, generate at every point of the image neighbourhood (stalkMap_germ_invApp; the stalk map is bijective).

            noncomputable def AnalyticSpace.GlueOver.glueClosedSubspace {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (hc : G.CompatClosedSubspaces C) :

            The glued closed subspace of compatible closed subspaces of the pieces.

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              theorem AnalyticSpace.GlueOver.comap_ιGlued_glueClosedSubspace {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (hc : G.CompatClosedSubspaces C) (i : ι) :

              The glued closed subspace pulls back along the open immersion of every piece to the given one.

              The preimage of the glued support under the i-th immersion is the i-th support.

              theorem AnalyticSpace.GlueOver.ext_of_forall_comap_ιGlued_eq {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {E E' : G.gluedOver.ClosedSubspace} (h : ∀ (i : ι), QuotientSpace.comap (↑(G.ιGlued i)) E = QuotientSpace.comap (↑(G.ιGlued i)) E') :
              E = E'

              Uniqueness of descent: two closed subspaces of the glued space with the same pull-backs to every piece are equal (the pieces cover, and the stalk maps of the open immersions are isomorphisms).

              theorem AnalyticSpace.GlueOver.existsUnique_comap_ιGlued_eq {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] (C : (i : ι) → (R i).ClosedSubspace) (hc : G.CompatClosedSubspaces C) :
              ∃! E : G.gluedOver.ClosedSubspace, ∀ (i : ι), QuotientSpace.comap (↑(G.ιGlued i)) E = C i

              Existence and uniqueness of descent: compatible closed subspaces of the pieces are the pull-backs of exactly one closed subspace of the glued space.

              The support of the glued closed subspace is the union of the images of the pieces' supports.

              The family layer: labelled families of closed subspaces glue #

              The hypothesis is the labelled form: a label type Λ, per-piece labels lab i : κ i → Λ injective on each piece, and for every label the members carrying it compatible across the transitions, with the empty subspace ⊤ standing in where a piece has no member with that label (so a member absent from a neighbouring piece must not meet the overlap: the totality clause, and the convention on empty members).

              The unit ideal sheaf (the empty closed subspace) has empty support.

              noncomputable def AnalyticSpace.GlueOver.memberOfLabel {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} (H : (i : ι) → κ i → (R i).ClosedSubspace) (lab : (i : ι) → κ i → Λ) (i : ι) (l : Λ) :

              The member of the i-th family carrying the label l; the empty subspace ⊤ when no member of the piece carries l.

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                theorem AnalyticSpace.GlueOver.memberOfLabel_lab {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (i : ι) (k : κ i) :
                memberOfLabel H lab i (lab i k) = H i k

                With injective labels, the member of the label lab i k is the member k.

                theorem AnalyticSpace.GlueOver.memberOfLabel_of_not_exists {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} {i : ι} {l : Λ} (h : ¬∃ (k : κ i), lab i k = l) :
                memberOfLabel H lab i l = ⊤

                A label carried by no member of the piece gives the empty subspace ⊤.

                theorem AnalyticSpace.GlueOver.support_memberOfLabel_subset {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} (H : (i : ι) → κ i → (R i).ClosedSubspace) (lab : (i : ι) → κ i → Λ) (i : ι) (l : Λ) :

                The support of a label's member lies in the piece's total support.

                theorem AnalyticSpace.GlueOver.iUnion_support_memberOfLabel {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (i : ι) :
                ⋃ (l : Λ), Manifold.IdealSheaf.support (memberOfLabel H lab i l) = ⋃ (k : κ i), Manifold.IdealSheaf.support (H i k)

                The labels' members have the piece's total support: every member appears at its own label, and absent labels contribute the empty set.

                theorem AnalyticSpace.GlueOver.exists_of_mem_support_memberOfLabel {K : Type} [RCLike K] {ι : Type u} {R : ι → AnalyticSpace K} {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) {i : ι} {l : Λ} {y : ↑↑(R i).toPresheafedSpace} (h : y ∈ Manifold.IdealSheaf.support (memberOfLabel H lab i l)) :
                ∃ (k : κ i), lab i k = l ∧ y ∈ Manifold.IdealSheaf.support (H i k)

                A point in the support of a label's member lies in the support of a member carrying that label.

                def AnalyticSpace.GlueOver.LabelledCompat {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) {Λ : Type u} {κ : ι → Type u} (H : (i : ι) → κ i → (R i).ClosedSubspace) (lab : (i : ι) → κ i → Λ) :

                Labelled compatibility of families: for every label, the members carrying it are compatible closed subspaces of the pieces (⊤ where a piece has no member with that label).

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                  noncomputable def AnalyticSpace.GlueOver.glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} (H : (i : ι) → κ i → (R i).ClosedSubspace) (lab : (i : ι) → κ i → Λ) (hc : G.LabelledCompat H lab) :

                  The glued family, indexed by the labels: the label l glues the members carrying it.

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                    theorem AnalyticSpace.GlueOver.comap_ιGlued_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hc : G.LabelledCompat H lab) (l : Λ) (i : ι) :
                    QuotientSpace.comap (↑(G.ιGlued i)) (G.glueFamily H lab hc l) = memberOfLabel H lab i l

                    The glued member with label l pulls back along ιGlued i to the i-th piece's member of that label (⊤ when the piece has none).

                    theorem AnalyticSpace.GlueOver.comap_ιGlued_glueFamily_lab {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (hc : G.LabelledCompat H lab) (i : ι) (k : κ i) :
                    QuotientSpace.comap (↑(G.ιGlued i)) (G.glueFamily H lab hc (lab i k)) = H i k

                    Pulled back to the i-th piece, the glued member with label lab i k is the member k.

                    theorem AnalyticSpace.GlueOver.preimage_support_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hc : G.LabelledCompat H lab) (l : Λ) (i : ι) :

                    The preimage under ιGlued i of a glued member's support is the support of the piece's member of that label.

                    theorem AnalyticSpace.GlueOver.support_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hc : G.LabelledCompat H lab) (l : Λ) :

                    The support of a glued member is the union of the images of the pieces' members of that label.

                    theorem AnalyticSpace.GlueOver.iUnion_support_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (hc : G.LabelledCompat H lab) :
                    ⋃ (l : Λ), Manifold.IdealSheaf.support (G.glueFamily H lab hc l) = ⋃ (i : ι), KLocallyRingedSpace.Hom.toFun (G.ιGlued i) '' ⋃ (k : κ i), Manifold.IdealSheaf.support (H i k)

                    The total support of the glued family is the union of the images of the pieces' total supports.

                    theorem AnalyticSpace.GlueOver.locallyFinite_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (hc : G.LabelledCompat H lab) (hfin : ∀ (i : ι), LocallyFinite fun (k : κ i) => Manifold.IdealSheaf.support (H i k)) :

                    Local finiteness of the glued family, from local finiteness on every piece.

                    theorem AnalyticSpace.GlueOver.isSncFamily_glueFamily {K : Type} [RCLike K] {X : AnalyticSpace K} {ι : Type u} {R : ι → AnalyticSpace K} {π : (i : ι) → (R i).toKLocallyRingedSpace ⟶ X.toKLocallyRingedSpace} {dom : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace} (G : X.GlueOver R π dom) [Countable ι] {Λ : Type u} {κ : ι → Type u} {H : (i : ι) → κ i → (R i).ClosedSubspace} {lab : (i : ι) → κ i → Λ} (hlab : ∀ (i : ι), Function.Injective (lab i)) (hc : G.LabelledCompat H lab) (hsnc : ∀ (i : ι), ClosedSubspace.IsSncFamily (H i)) :

                    Simple normal crossings glue ([Kol07, Definition 24], the local form of the divisor with simple normal crossings; ClosedSubspace.IsSncFamily): the glued family of labelled simple-normal-crossings families is one: the stalk data at a glued point are the piece's, carried through the stalk isomorphism of the open immersion; the glued members through the point are the piece's members through its representative, matched by the labels.