Documentation

LeanPool.ClassificationOfSurfaces.Moise.LocallyFiniteTriangulation

Locally finite triangle complexes #

Rado's induction in Moise Chapter 8 passes through locally finite, usually noncompact, PL complexes. Requiring every intermediate complex to be finite loses the frontier-vanishing construction used in the induction step. This file provides the corresponding ambient API while keeping the existing finite GeometricTriangulation as the final output.

A face is parametrized by the standard simplex on its three global vertices. The faceMap_eq_iff field says both that parametrizations agree on common faces and that distinct geometric points are never identified. Thus the structure records the full face-to-face condition, rather than only a family of carriers. Local finiteness is imposed on the carrier family in the ambient topology.

The main result is LocallyFiniteTriangleComplex.toGeometricTriangulation: on a compact Hausdorff space, local finiteness makes the face type finite; the no-junk-vertices condition then makes the vertex type finite, and finite closed pasting produces the required homeomorphism from the canonical barycentric realization.

Extend barycentric coordinates on a finite face by zero to the global vertex type.

Equations
Instances For

    Relabeling a finite face along an embedding #

    noncomputable def LeanEval.Topology.ClassificationOfSurfaces.Moise.finsetMapSubtypeEquiv {A : Type u_1} {B : Type u_2} (e : A B) (t : Finset A) :
    t (Finset.map e t)

    The vertices of a finite face are equivalent to the vertices of its image under an embedding.

    Equations
    Instances For
      @[simp]
      theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.finsetMapSubtypeEquiv_apply_val {A : Type u_1} {B : Type u_2} (e : A B) (t : Finset A) (a : t) :
      ((finsetMapSubtypeEquiv e t) a) = e a
      noncomputable def LeanEval.Topology.ClassificationOfSurfaces.Moise.relabelFaceSimplex {A : Type u_1} {B : Type u_2} (e : A B) (t : Finset A) (x : (stdSimplex (Finset.map e t))) :
      (stdSimplex t)

      Pull simplex coordinates on a relabeled face back to the original face.

      Equations
      Instances For

        Face relabeling along an embedding is onto.

        Pulling coordinates back along a face relabeling preserves the coordinate at every original vertex.

        Relabeling two faces by the same embedding preserves equality of their global zero-extended coordinate functions.

        theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.sum_extendFaceCoordinates_relabelFaceSimplex {A : Type u_1} {B : Type u_2} [Fintype A] [Fintype B] [DecidableEq A] [DecidableEq B] (e : A B) (t : Finset A) (x : (stdSimplex (Finset.map e t))) (F : B) :
        b : B, extendFaceCoordinates (Finset.map e t) x b * F b = a : A, extendFaceCoordinates t (relabelFaceSimplex e t x) a * F (e a)

        Relabeling does not change a weighted evaluation of the zero-extended coordinates.

        When the source face is the whole finite type, remove the vacuous membership subtype after pulling coordinates back along an embedding.

        Equations
        • One or more equations did not get rendered due to their size.
        Instances For
          noncomputable def LeanEval.Topology.ClassificationOfSurfaces.Moise.relabelUnivSimplex {A : Type u_1} {B : Type u_2} [Fintype A] (e : A B) (x : (stdSimplex (Finset.map e Finset.univ))) :

          Pull simplex coordinates on the image of a finite type back to that finite type.

          Equations
          Instances For

            Pullback along an embedded whole finite vertex type is onto: its inverse simply pushes coordinates forward along the inverse equivalence onto the image.

            The whole-type relabeling preserves the coordinate of every embedded source vertex.

            theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.stdSimplex_map_embedding_apply {A : Type u_1} {B : Type u_2} [Fintype A] [Fintype B] (e : A B) (x : (stdSimplex A)) (a : A) :
            (stdSimplex.map (⇑e) x) (e a) = x a

            An injective vertex map preserves the coordinate at each source vertex.

            theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.stdSimplex_map_embedding_apply_of_notMem_range {A : Type u_1} {B : Type u_2} [Fintype A] [Fintype B] (e : A B) (x : (stdSimplex A)) {b : B} (hb : bSet.range e) :
            (stdSimplex.map (⇑e) x) b = 0

            An injective vertex map has zero coordinate away from its image.

            Relabel a finite face family along an embedding of its vertex type.

            Equations
            Instances For

              Regard a listed face as a face of the family obtained by injectively relabeling its vertices.

              Equations
              Instances For

                Injective vertex relabeling preserves dual adjacency of listed faces.

                Injective vertex relabeling carries a finite dual path to the relabeled family.

                Dual connectivity is preserved by an injective relabeling of the vertex type.

                theorem LeanEval.Topology.ClassificationOfSurfaces.TriangleFamily.hasCrossEdge_relabel_of_mapped_edge_eq {A : Type u_1} {B : Type u_2} {C : Type u_3} [DecidableEq C] (eleft : A C) (eright : B C) {left : Finset (Finset A)} {right : Finset (Finset B)} (fleft : Face left) (fright : Face right) (edgeLeft : Finset A) (edgeRight : Finset B) (hedgeCard : edgeLeft.card = 2) (hedgeLeft : edgeLeftfleft) (hedgeRight : edgeRightfright) (hmap : Finset.map eleft edgeLeft = Finset.map eright edgeRight) :

                Faces relabeled from different vertex types share an edge when the two source edges have the same relabeled image.

                A shared edge remains a shared edge when both families are injectively relabeled.

                Push a geometric realization forward along an injective relabeling of all vertices.

                Equations
                Instances For

                  Pull a point of a relabeled realization back to its original vertex type.

                  Equations
                  Instances For
                    @[simp]
                    @[simp]

                    Relabeling a finite face family along a vertex embedding does not change its realization.

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

                      Weighted evaluation is unchanged by whole-type relabeling.

                      theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.sum_attach_mul_eq_sum_extendFaceCoordinates {V : Type u_1} [DecidableEq V] (t : Finset V) (x : (stdSimplex t)) (F : V) :
                      v : t, x v * F v = vt, extendFaceCoordinates t x v * F v

                      A sum over the subtype of a finite face is the corresponding sum of its zero-extended coordinates over the underlying vertex set.

                      theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.sum_extendFaceCoordinates_eq_of_eq {V : Type u_1} [DecidableEq V] {s t : Finset V} (x : (stdSimplex s)) (y : (stdSimplex t)) (hxy : extendFaceCoordinates s x = extendFaceCoordinates t y) (F : V) :
                      v : s, x v * F v = v : t, y v * F v

                      Equal zero-extended coordinates give equal weighted sums against any scalar-valued function on the global vertex type.

                      A locally finite family of parametrized triangles in an ambient topological space.

                      vertex_used excludes irrelevant vertices. This matters in the compactness-to-finiteness bridge: local finiteness controls the number of nonempty faces, and every vertex must then occur in one of those faces.

                      Instances For

                        The ambient support of the locally finite complex.

                        Equations
                        Instances For

                          A chosen maximal face incident to a global vertex.

                          Equations
                          Instances For

                            The ambient point represented by a global vertex.

                            Equations
                            Instances For

                              Every incident face parametrization sends a shared abstract vertex to the same ambient point.

                              Singleton carriers of the global vertices form a locally finite family.

                              Cyclic data on a maximal face #

                              A chosen cyclic enumeration of the three vertices of a maximal face.

                              Equations
                              Instances For

                                Cyclically indexed vertices of a maximal face.

                                Equations
                                Instances For

                                  Edges #

                                  A two-element vertex set contained in a maximal face.

                                  Equations
                                  Instances For
                                    @[reducible, inline]

                                    The edge type of a locally finite triangle complex.

                                    Equations
                                    Instances For

                                      The chosen first endpoint of an edge.

                                      Equations
                                      Instances For

                                        The chosen second endpoint of an edge.

                                        Equations
                                        Instances For

                                          The edge joining two consecutive cyclic vertices of a maximal face.

                                          Equations
                                          Instances For

                                            Consecutive face edges share exactly their common cyclic vertex.

                                            The arbitrary endpoint ordering of a cyclic face edge is one of its two cyclic orientations.

                                            The standard one-simplex point at interval parameter r.

                                            Equations
                                            Instances For

                                              A chosen maximal face incident to an edge.

                                              Equations
                                              Instances For

                                                Include edge-local vertices into a chosen incident maximal face.

                                                Equations
                                                Instances For

                                                  Parametrization of a closed edge by its standard one-simplex.

                                                  Equations
                                                  Instances For

                                                    The canonical interval parametrization of an ambient edge carrier.

                                                    Equations
                                                    Instances For
                                                      theorem LeanEval.Topology.ClassificationOfSurfaces.Moise.LocallyFiniteTriangleComplex.edgeMap_eq_faceMap {S : Type u_1} [TopologicalSpace S] (K : LocallyFiniteTriangleComplex S) (e : K.Edge) (f : K.Face) (hef : eK.faceVertices f) (x : (stdSimplex e)) :
                                                      K.edgeMap e x = K.faceMap f (stdSimplex.map (fun (v : e) => v, ) x)

                                                      Distinct edge carriers meet only at points represented by their shared abstract vertices.

                                                      The one-skeleton carrier of a locally finite triangle complex.

                                                      Equations
                                                      Instances For

                                                        The canonical interval parameter of a point known to lie on an edge carrier.

                                                        Equations
                                                        Instances For

                                                          The interval parametrization with codomain restricted to the edge carrier.

                                                          Equations
                                                          Instances For

                                                            Every closed edge carrier is canonically homeomorphic to the unit interval.

                                                            Equations
                                                            Instances For

                                                              The union of all edges not incident to a fixed vertex is closed.

                                                              @[implicit_reducible]

                                                              Local finiteness on a compact ambient space makes the type of maximal faces finite.

                                                              Equations
                                                              Instances For

                                                                If the face type is finite and every vertex is used, then the global vertex type is finite.

                                                                @[implicit_reducible]

                                                                The finite vertex instance induced by compactness and the no-junk-vertices condition.

                                                                Equations
                                                                Instances For

                                                                  The finite intrinsic complex obtained from a compact locally finite triangle complex.

                                                                  Equations
                                                                  Instances For

                                                                    Restrict a global standard-simplex point supported on t to the coordinates indexed by t.

                                                                    Equations
                                                                    Instances For

                                                                      Every point of the compact realization is supported on one of the original maximal faces.

                                                                      A canonical maximal face containing a point of the compact realization.

                                                                      Equations
                                                                      Instances For

                                                                        Evaluation of the compact barycentric realization through the locally finite face maps.

                                                                        Equations
                                                                        Instances For

                                                                          The compact evaluation has exactly the ambient support of the locally finite complex as its range.

                                                                          A locally finite triangle complex covering a compact Hausdorff space is an honest finite geometric triangulation.

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

                                                                            Finite complexes on their own support #

                                                                            Regard a finite ambient triangle complex as a complex whose ambient space is exactly its support. This is the finite gluing bridge used in the Rado induction: once a compatible finite family of old and new triangles has been assembled, no separate ambient coverage proof is needed.

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

                                                                              A finite ambient triangle complex has compact support, independently of compactness of the ambient space.

                                                                              Include the standard simplex on one maximal face into the global barycentric realization.

                                                                              Equations
                                                                              Instances For
                                                                                noncomputable def LeanEval.Topology.ClassificationOfSurfaces.Moise.IntrinsicTwoComplex.restrictToFaceSimplex (K : IntrinsicTwoComplex) (t : K.Face) (x : K.realization) (hx : vt, x v = 0) :
                                                                                (stdSimplex t)

                                                                                Restrict an intrinsic realization point supported on one maximal face to that face's standard simplex.

                                                                                Equations
                                                                                Instances For

                                                                                  Regard a finite intrinsic complex with no unused vertices as a locally finite ambient triangle complex.

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