Documentation

Hironaka.AnalyticSpace.HomGlue

Gluing morphisms of locally ringed spaces along an open cover #

Morphisms of locally ringed spaces g i : X | Uᵢ → W defined on the members of an open cover of X and agreeing on the overlaps X | (Uᵢ ⊓ Uⱼ) glue to a morphism X → W restricting to the g i — the existence half of the locality of morphisms (Hironaka/AnalyticSpace/HomLocal.lean is the uniqueness half). Hironaka's universal mapping property (**) of a monoidal transformation [Hir64, Ch. 0, §2] needs it: the lift of a test pair (Y', f') into the blow-up is constructed on the members of an open cover of Y' (over the complement of the centre and in each blow-up chart) and glued; the pieces agree on the overlaps by uniqueness. Elementary sheaf theory, not in the sources; stated for general locally ringed spaces.

Mathlib has LocallyRingedSpace.GlueData (gluing spaces), IsOpenImmersion.lift and the sheaf-level existsUnique_gluing', but no gluing of morphisms out of a space covered by opens; Scheme.OpenCover.glueMorphisms is for schemes.

The inclusion X | V → X | W of the restrictions to nested opens V ≤ W, as a morphism of presheafed spaces: the inclusion of subtypes on points, restriction of sections along the inclusion of image opens on sheaves.

Equations
  • One or more equations did not get rendered due to their size.
Instances For

    The stalk map of the inclusion X | V → X | W is an isomorphism (the two ofRestrict stalk maps are).

    The inclusion X | V → X | W of the restrictions to nested opens V ≤ W, as a morphism of locally ringed spaces.

    Equations
    Instances For

      The pieces g i : X | Uᵢ → W agree on the overlaps X | (Uᵢ ⊓ Uⱼ).

      Equations
      • One or more equations did not get rendered due to their size.
      Instances For
        theorem AnalyticSpace.exists_mem_nhds_of_cover {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (x : ↑X.toTopCat) :
        ∃ (i : ι), ↑(U i) ∈ nhds x

        The members of the cover are neighbourhoods of every point.

        noncomputable def AnalyticSpace.glueCoverBase {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) :

        The glued base map: x ↦ (g i).base x for any i with x ∈ Uᵢ.

        Equations
        • One or more equations did not get rendered due to their size.
        Instances For
          theorem AnalyticSpace.glueCoverBase_apply {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) (p : ↥(U i)) :

          The image in X of (g i).base ⁻¹ V ⊆ Uᵢ: the open on which the piece (g i)^* s lives.

          Equations
          Instances For

            The piece (g i)^* s, a section of X over gluePieceOpens i V.

            Equations
            Instances For
              theorem AnalyticSpace.gluePieceOpens_le {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) (V : TopologicalSpace.Opens ↑W.toTopCat) :
              theorem AnalyticSpace.le_iSup_gluePieceOpens {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) :
              (TopologicalSpace.Opens.map (glueCoverBase U g hU hg)).obj V ≤ ⨆ (i : ι), gluePieceOpens U g i V

              The germ of a piece at a point, through the overlap space X | (Uᵢ ⊓ Uⱼ): the piece of g k restricted along X | (Uᵢ ⊓ Uⱼ) → X | U_k has the germ of the piece itself.

              theorem AnalyticSpace.gluePieceSection_isCompatible {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) (s : ↑(W.presheaf.obj (Opposite.op V))) :
              X.presheaf.IsCompatible (fun (i : ι) => gluePieceOpens U g i V) fun (i : ι) => gluePieceSection U g i V s

              The pieces (g i)^* s are compatible on the overlaps (their germs agree, through the overlap space, because the pieces agree there).

              noncomputable def AnalyticSpace.glueSection {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) (s : ↑(W.presheaf.obj (Opposite.op V))) :

              The glued section over b⁻¹ V, b the glued base map: the unique section restricting to the piece (g i)^* s on every gluePieceOpens i V.

              Equations
              Instances For
                theorem AnalyticSpace.glueSection_res {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) (s : ↑(W.presheaf.obj (Opposite.op V))) (i : ι) :
                theorem AnalyticSpace.eq_glueSection {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) (s : ↑(W.presheaf.obj (Opposite.op V))) (t : ↑(X.presheaf.obj (Opposite.op ((TopologicalSpace.Opens.map (glueCoverBase U g hU hg)).obj V)))) (ht : ∀ (i : ι), (CategoryTheory.ConcreteCategory.hom (X.presheaf.map (CategoryTheory.homOfLE ⋯).op)) t = gluePieceSection U g i V s) :
                t = glueSection U g hU hg V s
                noncomputable def AnalyticSpace.glueSectionHom {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) :

                The glued sections form a ring homomorphism 𝒪_W(V) → 𝒪_X(b⁻¹ V).

                Equations
                Instances For
                  theorem AnalyticSpace.glueSectionHom_apply {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (V : TopologicalSpace.Opens ↑W.toTopCat) (s : ↑(W.presheaf.obj (Opposite.op V))) :
                  (CommRingCat.Hom.hom (glueSectionHom U g hU hg V)) s = glueSection U g hU hg V s
                  noncomputable def AnalyticSpace.glueCoverC {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) :

                  The sheaf component of the glued morphism.

                  Equations
                  Instances For
                    noncomputable def AnalyticSpace.glueHom {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) :

                    The glued morphism of presheafed spaces.

                    Equations
                    Instances For
                      theorem AnalyticSpace.glueHom_base_apply {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) (p : ↥(U i)) :
                      theorem AnalyticSpace.inseparable_glueCoverBase {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) {x : ↑X.toTopCat} (hi : x ∈ U i) :

                      The stalk map of the glued morphism at a point of Uᵢ is the stalk map of g i, read through the identification of the image points and the stalk of the open subspace.

                      noncomputable def AnalyticSpace.glueOfCover {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) :
                      X ⟶ W

                      The morphism of locally ringed spaces glued from compatible pieces g i : X | Uᵢ → W along an open cover of X.

                      Equations
                      Instances For
                        theorem AnalyticSpace.glueOfCover_base_apply {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) (p : ↥(U i)) :
                        theorem AnalyticSpace.ofRestrict_comp_glueOfCover {X : AlgebraicGeometry.LocallyRingedSpace} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑X.toTopCat) {W : AlgebraicGeometry.LocallyRingedSpace} (g : (i : ι) → X.restrict ⋯ ⟶ W) (hU : ∀ (x : ↑X.toTopCat), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) :

                        The glued morphism restricts to the pieces.

                        The inclusion X | V → X | W of the open subspaces of nested opens V ≤ W, as a K-morphism (the factorization of X | V → X through X | W → X).

                        Equations
                        Instances For

                          The K-morphisms g i : X | Uᵢ → W agree on the overlaps X | (Uᵢ ⊓ Uⱼ).

                          Equations
                          • One or more equations did not get rendered due to their size.
                          Instances For
                            theorem AnalyticSpace.KLocallyRingedSpace.GlueCompatible.val {K : Type} [RCLike K] {X : KLocallyRingedSpace K} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace) {W : KLocallyRingedSpace K} (g : (i : ι) → X.restrictOpen (U i) ⟶ W) (hg : GlueCompatible U g) :
                            AnalyticSpace.GlueCompatible U fun (i : ι) => ↑(g i)
                            noncomputable def AnalyticSpace.KLocallyRingedSpace.glueOfCover {K : Type} [RCLike K] {X : KLocallyRingedSpace K} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace) {W : KLocallyRingedSpace K} (g : (i : ι) → X.restrictOpen (U i) ⟶ W) (hU : ∀ (x : ↑↑X.toPresheafedSpace), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) :
                            X ⟶ W

                            The K-morphism glued from compatible K-morphisms g i : X | Uᵢ → W along an open cover of X: the glued morphism of locally ringed spaces, which respects the K-structures because its global sections restrict to those of the pieces.

                            Equations
                            Instances For
                              theorem AnalyticSpace.KLocallyRingedSpace.ofRestrict_comp_glueOfCover {K : Type} [RCLike K] {X : KLocallyRingedSpace K} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace) {W : KLocallyRingedSpace K} (g : (i : ι) → X.restrictOpen (U i) ⟶ W) (hU : ∀ (x : ↑↑X.toPresheafedSpace), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) :
                              theorem AnalyticSpace.KLocallyRingedSpace.glueOfCover_toFun_apply {K : Type} [RCLike K] {X : KLocallyRingedSpace K} {ι : Type u_1} (U : ι → TopologicalSpace.Opens ↑↑X.toPresheafedSpace) {W : KLocallyRingedSpace K} (g : (i : ι) → X.restrictOpen (U i) ⟶ W) (hU : ∀ (x : ↑↑X.toPresheafedSpace), ∃ (i : ι), x ∈ U i) (hg : GlueCompatible U g) (i : ι) (p : ↥(U i)) :
                              Hom.toFun (glueOfCover U g hU hg) ↑p = Hom.toFun (g i) p