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isEmbedding_singleton : IsEmbedding ({·} : α → NonemptyCompacts α)
isEmbedding_coe.of_comp_iff.mp vietoris.isEmbedding_singleton
theorem
TopologicalSpace.NonemptyCompacts.isEmbedding_singleton
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuous_singleton : Continuous ({·} : α → NonemptyCompacts α)
isEmbedding_singleton.continuous
theorem
TopologicalSpace.NonemptyCompacts.continuous_singleton
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "Continuous" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isClosedEmbedding_singleton [T2Space α] : Topology.IsClosedEmbedding ({·} : α → NonemptyCompacts α)
isClosedEmbedding_toCompacts.of_comp_iff.mp Compacts.isClosedEmbedding_singleton
theorem
TopologicalSpace.NonemptyCompacts.isClosedEmbedding_singleton
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "T2Space", "Topology.IsClosedEmbedding" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuous_prod : Continuous fun p : NonemptyCompacts α × NonemptyCompacts β => p.1 ×ˢ p.2
by simp_rw [isEmbedding_toCompacts.continuous_iff, Function.comp_def, toCompacts_prod] fun_prop
theorem
TopologicalSpace.NonemptyCompacts.continuous_prod
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "Continuous" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.Continuous.nonemptyCompacts_map (hf : Continuous f) : Continuous (NonemptyCompacts.map f hf)
isEmbedding_toCompacts.continuous_iff.mpr <| hf.compacts_map.comp continuous_toCompacts
theorem
Continuous.nonemptyCompacts_map
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "Continuous" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.Topology.IsInducing.nonemptyCompacts_map (hf : IsInducing f) : IsInducing (NonemptyCompacts.map f hf.continuous)
.of_comp hf.continuous.nonemptyCompacts_map continuous_toCompacts <| hf.compacts_map.comp isEmbedding_toCompacts.isInducing
theorem
Topology.IsInducing.nonemptyCompacts_map
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.Topology.IsEmbedding.nonemptyCompacts_map (hf : IsEmbedding f) : IsEmbedding (NonemptyCompacts.map f hf.continuous)
where __ := hf.isInducing.nonemptyCompacts_map injective := map_injective hf.continuous hf.injective
theorem
Topology.IsEmbedding.nonemptyCompacts_map
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.Topology.IsOpenEmbedding.nonemptyCompacts_map (hf : IsOpenEmbedding f) : IsOpenEmbedding (NonemptyCompacts.map f hf.continuous)
.of_comp _ isOpenEmbedding_toCompacts <| hf.compacts_map.comp isOpenEmbedding_toCompacts
theorem
Topology.IsOpenEmbedding.nonemptyCompacts_map
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.Topology.IsClosedEmbedding.nonemptyCompacts_map (hf : IsClosedEmbedding f) : IsClosedEmbedding (NonemptyCompacts.map f hf.continuous)
isClosedEmbedding_toCompacts.of_comp_iff.mp <| hf.compacts_map.comp isClosedEmbedding_toCompacts
theorem
Topology.IsClosedEmbedding.nonemptyCompacts_map
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
discreteTopology_iff : DiscreteTopology (NonemptyCompacts α) ↔ DiscreteTopology α
⟨fun _ => isEmbedding_singleton.discreteTopology, fun _ => inferInstance⟩
theorem
TopologicalSpace.NonemptyCompacts.discreteTopology_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "DiscreteTopology" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
t2Space_iff : T2Space (NonemptyCompacts α) ↔ T2Space α
⟨fun _ => isEmbedding_singleton.t2Space, fun _ => inferInstance⟩
theorem
TopologicalSpace.NonemptyCompacts.t2Space_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "T2Space" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
regularSpace_iff : RegularSpace (NonemptyCompacts α) ↔ RegularSpace α
⟨fun _ => isEmbedding_singleton.regularSpace, fun _ => inferInstance⟩
theorem
TopologicalSpace.NonemptyCompacts.regularSpace_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "RegularSpace" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
t3Space_iff : T3Space (NonemptyCompacts α) ↔ T3Space α
⟨fun _ => isEmbedding_singleton.t3Space, fun _ => inferInstance⟩
theorem
TopologicalSpace.NonemptyCompacts.t3Space_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "T3Space" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isCompact_subsets_of_isCompact {K : Set α} (hK : IsCompact K) : IsCompact {L : NonemptyCompacts α | ↑L ⊆ K}
isClosedEmbedding_toCompacts.isCompact_preimage (Compacts.isCompact_subsets_of_isCompact hK)
theorem
TopologicalSpace.NonemptyCompacts.isCompact_subsets_of_isCompact
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "IsCompact", "Set" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isCompact_biUnion_coe_of_isCompact {S : Set (NonemptyCompacts α)} (hs : IsCompact S) : IsCompact (⋃ K ∈ S, (K : Set α))
by convert! Compacts.isCompact_biUnion_coe_of_isCompact (hs.image continuous_toCompacts) simp_rw [biUnion_image, coe_toCompacts]
theorem
TopologicalSpace.NonemptyCompacts.isCompact_biUnion_coe_of_isCompact
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "IsCompact", "Set" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
compactSpace_iff : CompactSpace (NonemptyCompacts α) ↔ CompactSpace α
by refine ⟨fun h => ⟨?_⟩, fun _ => inferInstance⟩ convert! isCompact_biUnion_coe_of_isCompact (α := α) isCompact_univ symm simp_rw [biUnion_univ, eq_univ_iff_forall, mem_iUnion] exact fun x => ⟨{x}, Set.mem_singleton x⟩
theorem
TopologicalSpace.NonemptyCompacts.compactSpace_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "CompactSpace", "Set.mem_singleton", "isCompact_univ", "symm" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
noncompactSpace_iff : NoncompactSpace (NonemptyCompacts α) ↔ NoncompactSpace α
by simp_rw [← not_compactSpace_iff, compactSpace_iff]
theorem
TopologicalSpace.NonemptyCompacts.noncompactSpace_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "NoncompactSpace", "not_compactSpace_iff" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
locallyCompactSpace_iff : LocallyCompactSpace (NonemptyCompacts α) ↔ LocallyCompactSpace α
by refine ⟨fun _ => ⟨fun x U hU => ?_⟩, fun _ => inferInstance⟩ rw [← mem_interior_iff_mem_nhds, ← singleton_subset_iff, ← coe_singleton] at hU obtain ⟨K, hK, hxK, hKU⟩ := exists_compact_subset (isOpen_subsets_of_isOpen isOpen_interior) hU refine ⟨⋃ L ∈ K, L, ?_, iUnion₂_subset <| by grind [interior_subset], ...
theorem
TopologicalSpace.NonemptyCompacts.locallyCompactSpace_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "LocallyCompactSpace", "exists_compact_subset", "interior_subset", "isOpen_interior", "mem_interior_iff_mem_nhds" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
_root_.TopologicalSpace.Compacts.locallyCompactSpace_iff : LocallyCompactSpace (Compacts α) ↔ LocallyCompactSpace α
⟨fun _ => NonemptyCompacts.locallyCompactSpace_iff.mp isOpenEmbedding_toCompacts.locallyCompactSpace, fun _ => inferInstance⟩
theorem
TopologicalSpace.Compacts.locallyCompactSpace_iff
Topology.Sets
Mathlib/Topology/Sets/VietorisTopology.lean
[]
[ "LocallyCompactSpace" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isZero_iff_stalkFunctor_obj_isZero (F : Sheaf C X) : IsZero F ↔ ∀ x : X, IsZero ((forget C X ⋙ stalkFunctor C x).obj F)
by refine ⟨fun h _ => Functor.map_isZero _ h, ?_⟩ intro h let f : F ⟶ 0 := (isZero_zero (Sheaf C X)).from_ F have : IsIso f := by rw [Presheaf.isIso_iff_stalkFunctor_map_iso] exact fun x => isIso_of_source_target_iso_zero _ (h x).isoZero ((forget C X ⋙ stalkFunctor C x).map_isZero (isZero_zero _))...
lemma
TopCat.Sheaf.isZero_iff_stalkFunctor_obj_isZero
Topology.Sheaves
Mathlib/Topology/Sheaves/Abelian.lean
[]
[]
A sheaf is zero if and only if its stalks are all zero.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
exact_iff_stalkFunctor_map_exact (S : ShortComplex (Sheaf C X)) : S.Exact ↔ ∀ x : X, (S.map (forget C X ⋙ stalkFunctor C x)).Exact
by constructor · intro h x have := (forget C X ⋙ stalkFunctor C x).exact_tfae.out 2 1 exact this.mp inferInstance S h intro h simp_rw [ShortComplex.exact_iff_isZero_homology] at h rw [ShortComplex.exact_iff_isZero_homology, isZero_iff_stalkFunctor_obj_isZero S.homology] exact fun x => (h x).of_iso ...
theorem
TopCat.Sheaf.exact_iff_stalkFunctor_map_exact
Topology.Sheaves
Mathlib/Topology/Sheaves/Abelian.lean
[]
[ "symm" ]
Exactness can be checked on stalks for complexes of sheaves.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Presheaf.sections_exact_of_exact {S : ShortComplex (Presheaf AddCommGrpCat.{u} X)} (hS : S.Exact) {s : S.X₂.obj (Opposite.op U)} (h : S.g.app (Opposite.op U) s = 0) : ∃ (t : S.X₁.obj (Opposite.op U)), S.f.app (Opposite.op U) t = s
by dsimp [Presheaf] at S let F := (evaluation (Opens X)ᵒᵖ AddCommGrpCat.{u}).obj (Opposite.op U) exact (ShortComplex.ab_exact_iff (S.map F)).mp (((Functor.exact_tfae F).out 1 3 rfl rfl).mpr ⟨inferInstance, inferInstance⟩ S hS) _ h
theorem
TopCat.Presheaf.sections_exact_of_exact
Topology.Sheaves
Mathlib/Topology/Sheaves/AddCommGrpCat.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Sheaf.sections_exact_of_left_exact {S : ShortComplex (TopCat.Sheaf AddCommGrpCat X)} (hS : S.Exact) (hf : Mono S.f) (s : S.X₂.obj.obj (Opposite.op U)) (h : S.g.hom.app (Opposite.op U) s = 0) : ∃ (t : S.X₁.obj.obj (Opposite.op U)), S.f.hom.app (Opposite.op U) t = s
Presheaf.sections_exact_of_exact (((Functor.preservesFiniteLimits_tfae (Sheaf.forget ..)).out 1 3 rfl rfl).mpr inferInstance S ⟨hS, hf⟩).left h
lemma
TopCat.Sheaf.sections_exact_of_left_exact
Topology.Sheaves
Mathlib/Topology/Sheaves/AddCommGrpCat.lean
[]
[ "AddCommGrpCat", "TopCat.Sheaf" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Presheaf.restrict_sum {V : Opens X} {F : Presheaf AddCommGrpCat X} (h : V ≤ U) (s t : F.obj (op U)) : (s + t) |_ V = s |_ V + t |_ V
by delta Presheaf.restrictOpen Presheaf.restrict cat_disch
lemma
TopCat.Presheaf.restrict_sum
Topology.Sheaves
Mathlib/Topology/Sheaves/AddCommGrpCat.lean
[]
[ "AddCommGrpCat" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
principalOpen (x : X) : Opens X
.mk { y | x ≤ y } <| by rw [IsUpperSet.isOpen_iff_isUpperSet] intro y z h1 h2 exact le_trans h2 h1
def
Alexandrov.principalOpen
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "le_trans" ]
Given `x : X`, this is the principal open subset of `X` generated by `x`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
self_mem_principalOpen (x : X) : x ∈ principalOpen x
le_refl _
lemma
Alexandrov.self_mem_principalOpen
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "le_refl" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
principalOpen_le_iff {x : X} (U : Opens X) : principalOpen x ≤ U ↔ x ∈ U
by refine ⟨fun h => h <| self_mem_principalOpen _, fun hx y hy => ?_⟩ · have := U.isOpen rw [IsUpperSet.isOpen_iff_isUpperSet] at this exact this hy hx
lemma
Alexandrov.principalOpen_le_iff
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
principalOpen_le {x y : X} (h : x ≤ y) : principalOpen y ≤ principalOpen x
fun _ hc => le_trans h hc
lemma
Alexandrov.principalOpen_le
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "le_trans" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
principals : X ⥤ (Opens X)ᵒᵖ
where obj x := .op <| principalOpen x map {x y} f := .op <| principalOpen_le f.le |>.hom
def
Alexandrov.principals
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[]
The functor sending `x : X` to the principal open associated with `x`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
exists_le_of_le_sup {ι : Type v} {x : X} (Us : ι → Opens X) (h : principalOpen x ≤ iSup Us) : ∃ i : ι, principalOpen x ≤ Us i
by grind [principalOpen_le_iff, Opens.mem_iSup]
lemma
Alexandrov.exists_le_of_le_sup
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "iSup" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
principalsKanExtension : (Opens X)ᵒᵖ ⥤ C
(principals X).pointwiseRightKanExtension F
abbrev
Alexandrov.principalsKanExtension
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[]
The right Kan extension of `F` along `X ⥤ (Opens X)ᵒᵖ`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
generator (U : Opens X) : StructuredArrow (.op U) (principals X) ⥤ X
StructuredArrow.proj (.op U) (principals X)
abbrev
Alexandrov.generator
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[]
Given a structured arrow `f` with domain `U : Opens X` over `principals X`, this functor sends `f` to its "generator", an element of `X`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
projSup {ι : Type v} (Us : ι → Opens X) : StructuredArrow (.op <| iSup Us) (principals X) ⥤ (OpensLeCover (X := .of X) Us)ᵒᵖ
where obj f := .op <| .mk (principalOpen f.right) <| exists_le_of_le_sup Us f.hom.unop.le map e := (ObjectProperty.homMk (homOfLE (principalOpen_le e.right.le))).op
def
Alexandrov.projSup
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "iSup" ]
Given a structured arrow `f` with domain `iSup Us` over `principals X`, where `Us` is a family of `Opens X`, this functor sends `f` to the principal open associated with it, considered as an object in the full subcategory of all `V : Opens X` such that `V ≤ Us i` for some `i`. This definition is primarily meant to be ...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
lowerCone {α : Type v} (Us : α → Opens X) (S : Cone ((ObjectProperty.ι _ : OpensLeCover (X := .of X) Us ⥤ _).op ⋙ principalsKanExtension F)) : Cone (generator (iSup Us) ⋙ F)
where pt := S.pt π := { app := fun f => S.π.app ((projSup Us).obj f) ≫ limit.π (generator (principalOpen f.right) ⋙ F) ⟨.mk .unit, f.right, 𝟙 _⟩ naturality := by rintro x y e simp only [Functor.const_obj_obj, Functor.comp_obj, Functor.const_obj_map, Functor.op_obj, Functor...
def
Alexandrov.lowerCone
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "LE.le.hom", "iSup", "symm", "trans" ]
This is an auxiliary definition which is only meant to be used in `isLimit` below.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isLimit {X : TopCat.{v}} [Preorder X] [Topology.IsUpperSet X] (F : X ⥤ C) (α : Type v) (Us : α → Opens X) : IsLimit (mapCone (principalsKanExtension F) (opensLeCoverCocone Us).op)
where lift S := limit.lift _ (lowerCone Us S) fac := by rintro S ⟨V, i, hV⟩ dsimp [forget, opensLeCoverCocone] ext ⟨_, x, f⟩ simp only [Category.assoc, limit.lift_π, lowerCone_pt, lowerCone_π_app, const_obj_obj, projSup_obj, StructuredArrow.map_obj_right, comp_obj, op_obj, pointwiseRightKanExt...
def
Alexandrov.isLimit
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "Preorder", "Topology.IsUpperSet", "le_trans", "symm", "trans" ]
This is the main construction in this file showing that the right Kan extension of `F : X ⥤ C` along `principals : X ⥤ (Opens X)ᵒᵖ` is a sheaf, by showing that a certain cone is a limit cone. See `isSheaf_principalsKanExtension` for the main application.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isSheaf_principalsKanExtension {X : TopCat.{v}} [Preorder X] [Topology.IsUpperSet X] (F : X ⥤ C) : Presheaf.IsSheaf (principalsKanExtension F)
by rw [isSheaf_iff_isSheafOpensLeCover] intro ι Us constructor apply isLimit
theorem
Alexandrov.isSheaf_principalsKanExtension
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "Preorder", "Topology.IsUpperSet" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Topology.IsUpperSet.isSheaf_of_isRightKanExtension (P : (Opens X)ᵒᵖ ⥤ C) (η : Alexandrov.principals X ⋙ P ⟶ F) [P.IsRightKanExtension η] : Presheaf.IsSheaf (Opens.grothendieckTopology X) P
by let γ : principals X ⋙ principalsKanExtension F ⟶ F := (principals X).pointwiseRightKanExtensionCounit F let _ : (principalsKanExtension F).IsRightKanExtension γ := inferInstance have : P ≅ principalsKanExtension F := @rightKanExtensionUnique _ _ _ _ _ _ _ _ _ _ (by assumption) _ _ (by assumption) ch...
theorem
Topology.IsUpperSet.isSheaf_of_isRightKanExtension
Topology.Sheaves
Mathlib/Topology/Sheaves/Alexandrov.lean
[]
[ "Alexandrov.principals", "Opens.grothendieckTopology", "Preorder", "TopCat.Presheaf.IsSheaf", "Topology.IsUpperSet" ]
The main theorem of this file. If `X` is a topological space and preorder whose topology is the `UpperSet` topology associated with the preorder, `F : X ⥤ C` is a functor into a complete category from the preorder category, and `P : (Opens X)ᵒᵖ ⥤ C` denotes the right Kan extension of `F` along the functor `X ⥤ (Open X)...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
restrictOpenCommRingCat_apply {X : TopCat.{w}} {F : Presheaf CommRingCat X} {V : Opens ↑X} (f : CommRingCat.carrier (F.obj (op V))) (U : Opens ↑X) (e : U ≤ V := by restrict_tac) : f |_ U = F.map (homOfLE e).op f
rfl
lemma
TopCat.Presheaf.restrictOpenCommRingCat_apply
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat" ]
Unfold `restrictOpen` in the category of commutative rings (with the correct carrier type). Although unification hints help with applying `TopCat.Presheaf.restrictOpenCommRingCat`, so it can be safely de-specialized, this lemma needs to be kept to ensure rewrites go right.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
SubmonoidPresheaf (F : X.Presheaf CommRingCat) where /-- The submonoid structure for each component -/ obj : ∀ U, Submonoid (F.obj U) map : ∀ {U V : (Opens X)ᵒᵖ} (i : U ⟶ V), obj U ≤ (obj V).comap (F.map i).hom
structure
TopCat.Presheaf.SubmonoidPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "Submonoid", "comap" ]
A subpresheaf with a submonoid structure on each of the components.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
SubmonoidPresheaf.localizationPresheaf : X.Presheaf CommRingCat
where obj U := CommRingCat.of <| Localization (G.obj U) map {_ _} i := CommRingCat.ofHom <| IsLocalization.map _ (F.map i).hom (G.map i) map_id U := by simp_rw [F.map_id] ext x exact IsLocalization.map_id x map_comp {U V W} i j := by delta CommRingCat.ofHom CommRingCat.of Bundled.of simp_rw ...
def
TopCat.Presheaf.SubmonoidPresheaf.localizationPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.ofHom", "IsLocalization.map", "IsLocalization.map_comp_map", "IsLocalization.map_id", "Localization" ]
The localization of a presheaf of `CommRing`s with respect to a `SubmonoidPresheaf`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
SubmonoidPresheaf.toLocalizationPresheaf : F ⟶ G.localizationPresheaf
where app U := CommRingCat.ofHom <| algebraMap (F.obj U) (Localization <| G.obj U) naturality {_ _} i := CommRingCat.hom_ext <| (IsLocalization.map_comp (G.map i)).symm
def
TopCat.Presheaf.SubmonoidPresheaf.toLocalizationPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat.hom_ext", "CommRingCat.ofHom", "IsLocalization.map_comp", "Localization", "symm" ]
The map into the localization presheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
epi_toLocalizationPresheaf : Epi G.toLocalizationPresheaf
@NatTrans.epi_of_epi_app _ _ _ _ _ _ G.toLocalizationPresheaf fun U => Localization.epi' (G.obj U)
instance
TopCat.Presheaf.epi_toLocalizationPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "Localization.epi'" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
submonoidPresheafOfStalk (S : ∀ x : X, Submonoid (F.stalk x)) : F.SubmonoidPresheaf
where obj U := ⨅ x : U.unop, Submonoid.comap (F.germ U.unop x.1 x.2).hom (S x) map {U V} i := by intro s hs simp only [Submonoid.mem_comap, Submonoid.mem_iInf] at hs ⊢ intro x change (F.map i.unop.op ≫ F.germ V.unop x.1 x.2) s ∈ _ rw [F.germ_res] exact hs ⟨_, i.unop.le x.2⟩
def
TopCat.Presheaf.submonoidPresheafOfStalk
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "Submonoid", "Submonoid.comap", "Submonoid.mem_comap", "Submonoid.mem_iInf" ]
Given a submonoid at each of the stalks, we may define a submonoid presheaf consisting of sections whose restriction onto each stalk falls in the given submonoid.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
totalQuotientPresheaf : X.Presheaf CommRingCat.{w}
(F.submonoidPresheafOfStalk fun x => (F.stalk x)⁰).localizationPresheaf
def
TopCat.Presheaf.totalQuotientPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[]
The localization of a presheaf of `CommRing`s at locally non-zero-divisor sections.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
toTotalQuotientPresheaf : F ⟶ F.totalQuotientPresheaf
SubmonoidPresheaf.toLocalizationPresheaf _ deriving Epi
def
TopCat.Presheaf.toTotalQuotientPresheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[]
The map into the presheaf of total quotient rings
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuousFunctions (X : TopCat.{v}ᵒᵖ) (R : TopCommRingCat.{v}) : CommRingCat.{v}
CommRingCat.of (X.unop ⟶ (forget₂ TopCommRingCat TopCat).obj R)
def
TopCat.continuousFunctions
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "TopCat", "TopCommRingCat" ]
The (bundled) commutative ring of continuous functions from a topological space to a topological commutative ring, with pointwise multiplication.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pullback {X Y : TopCatᵒᵖ} (f : X ⟶ Y) (R : TopCommRingCat) : continuousFunctions X R ⟶ continuousFunctions Y R
CommRingCat.ofHom { toFun g := f.unop ≫ g map_one' := rfl map_zero' := rfl map_add' := by cat_disch map_mul' := by cat_disch }
def
TopCat.continuousFunctions.pullback
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat.ofHom", "TopCommRingCat" ]
Pulling back functions into a topological ring along a continuous map is a ring homomorphism.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
map (X : TopCat.{u}ᵒᵖ) {R S : TopCommRingCat.{u}} (φ : R ⟶ S) : continuousFunctions X R ⟶ continuousFunctions X S
CommRingCat.ofHom { toFun g := g ≫ (forget₂ TopCommRingCat TopCat).map φ map_one' := by ext; exact φ.1.map_one map_zero' := by ext; exact φ.1.map_zero map_add' _ _ := by ext; exact φ.1.map_add _ _ map_mul' _ _ := by ext; exact φ.1.map_mul _ _ }
def
TopCat.continuousFunctions.map
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat.ofHom", "TopCat", "TopCommRingCat" ]
A homomorphism of topological rings can be postcomposed with functions from a source space `X`; this is a ring homomorphism (with respect to the pointwise ring operations on functions).
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
commRingYoneda : TopCommRingCat.{u} ⥤ TopCat.{u}ᵒᵖ ⥤ CommRingCat.{u}
where obj R := { obj := fun X => continuousFunctions X R map := fun {_ _} f => continuousFunctions.pullback f R map_id := fun X => by ext rfl map_comp := fun {_ _ _} _ _ => rfl } map {_ _} φ := { app := fun X => continuousFunctions.map X φ naturality := fun _ _ _ => r...
def
TopCat.commRingYoneda
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[]
An upgraded version of the Yoneda embedding, observing that the continuous maps from `X : TopCat` to `R : TopCommRingCat` form a commutative ring, functorial in both `X` and `R`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
presheafToTopCommRing (T : TopCommRingCat.{v}) : X.Presheaf CommRingCat.{v}
(Opens.toTopCat X).op ⋙ commRingYoneda.obj T
def
TopCat.presheafToTopCommRing
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[]
The presheaf (of commutative rings), consisting of functions on an open set `U ⊆ X` with values in some topological commutative ring `T`. For example, we could construct the presheaf of continuous complex-valued functions of `X` as ``` presheafToTopCommRing X (TopCommRingCat.of ℂ) ``` (this requires `import Topology.I...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
algebra_section_stalk (F : X.Presheaf CommRingCat) {U : Opens X} (x : U) : Algebra (F.obj <| op U) (F.stalk x)
(F.germ U x.1 x.2).hom.toAlgebra
instance
TopCat.Presheaf.algebra_section_stalk
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "Algebra", "CommRingCat" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
stalk_open_algebraMap {X : TopCat.{v}} (F : X.Presheaf CommRingCat) {U : Opens X} (x : U) : algebraMap (F.obj <| op U) (F.stalk x) = (F.germ U x.1 x.2).hom
rfl
theorem
TopCat.Presheaf.stalk_open_algebraMap
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus {X : TopCat.{w}} (F : X.Sheaf CommRingCat) (U V : Opens X) : F.1.obj (op <| U ⊔ V) ≅ CommRingCat.of <| -- Porting note: Lean 3 is able to figure out the ring homomorphism automatically RingHom.eqLocus (RingHom.comp (F.obj.map (homOfLE inf_le_left : U ⊓ V ⟶ U).op).hom (Ring...
(F.isLimitPullbackCone U V).conePointUniqueUpToIso (CommRingCat.pullbackConeIsLimit _ _)
def
TopCat.Sheaf.objSupIsoProdEqLocus
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.pullbackConeIsLimit", "RingHom.comp", "RingHom.eqLocus", "RingHom.fst", "RingHom.snd" ]
`F(U ⊔ V)` is isomorphic to the `eq_locus` of the two maps `F(U) × F(V) ⟶ F(U ⊓ V)`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus_hom_fst {X : TopCat.{w}} (F : X.Sheaf CommRingCat) (U V : Opens X) (x) : ((F.objSupIsoProdEqLocus U V).hom x).1.fst = F.1.map (homOfLE le_sup_left).op x
ConcreteCategory.congr_hom ((F.isLimitPullbackCone U V).conePointUniqueUpToIso_hom_comp (CommRingCat.pullbackConeIsLimit _ _) WalkingCospan.left) x
theorem
TopCat.Sheaf.objSupIsoProdEqLocus_hom_fst
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.pullbackConeIsLimit", "le_sup_left" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus_hom_snd {X : TopCat.{w}} (F : X.Sheaf CommRingCat) (U V : Opens X) (x) : ((F.objSupIsoProdEqLocus U V).hom x).1.snd = F.1.map (homOfLE le_sup_right).op x
ConcreteCategory.congr_hom ((F.isLimitPullbackCone U V).conePointUniqueUpToIso_hom_comp (CommRingCat.pullbackConeIsLimit _ _) WalkingCospan.right) x
theorem
TopCat.Sheaf.objSupIsoProdEqLocus_hom_snd
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.pullbackConeIsLimit", "le_sup_right" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus_inv_fst {X : TopCat.{w}} (F : X.Sheaf CommRingCat) (U V : Opens X) (x) : F.1.map (homOfLE le_sup_left).op ((F.objSupIsoProdEqLocus U V).inv x) = x.1.1
ConcreteCategory.congr_hom ((F.isLimitPullbackCone U V).conePointUniqueUpToIso_inv_comp (CommRingCat.pullbackConeIsLimit _ _) WalkingCospan.left) x
theorem
TopCat.Sheaf.objSupIsoProdEqLocus_inv_fst
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.pullbackConeIsLimit", "le_sup_left" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus_inv_snd {X : TopCat.{w}} (F : X.Sheaf CommRingCat) (U V : Opens X) (x) : F.1.map (homOfLE le_sup_right).op ((F.objSupIsoProdEqLocus U V).inv x) = x.1.2
ConcreteCategory.congr_hom ((F.isLimitPullbackCone U V).conePointUniqueUpToIso_inv_comp (CommRingCat.pullbackConeIsLimit _ _) WalkingCospan.right) x
theorem
TopCat.Sheaf.objSupIsoProdEqLocus_inv_snd
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat", "CommRingCat.pullbackConeIsLimit", "le_sup_right" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
objSupIsoProdEqLocus_inv_eq_iff {X : TopCat.{u}} (F : X.Sheaf CommRingCat.{u}) {U V W UW VW : Opens X} (e : W ≤ U ⊔ V) (x) (y : F.1.obj (op W)) (h₁ : UW = U ⊓ W) (h₂ : VW = V ⊓ W) : F.1.map (homOfLE e).op ((F.objSupIsoProdEqLocus U V).inv x) = y ↔ F.1.map (homOfLE (h₁ ▸ inf_le_left : UW ≤ U)).op x.1.1 =...
by subst h₁ h₂ constructor · rintro rfl rw [← TopCat.Sheaf.objSupIsoProdEqLocus_inv_fst, ← TopCat.Sheaf.objSupIsoProdEqLocus_inv_snd] simp only [← CommRingCat.comp_apply, ← Functor.map_comp, ← op_comp, homOfLE_comp, and_self] · rintro ⟨e₁, e₂⟩ refine F.eq_of_locally_eq₂ (homOfLE (inf_le_...
theorem
TopCat.Sheaf.objSupIsoProdEqLocus_inv_eq_iff
Topology.Sheaves
Mathlib/Topology/Sheaves/CommRingCat.lean
[]
[ "CommRingCat.comp_apply", "TopCat.Sheaf.objSupIsoProdEqLocus_inv_fst", "TopCat.Sheaf.objSupIsoProdEqLocus_inv_snd", "inf_sup_right", "le_rfl" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
EtaleSpace (F : Presheaf C X) where /-- The base point. -/ base : X /-- A germ at `base` (formally, an element of the stalk of `F` at `base`). -/ germ : ToType (F.stalk base)
structure
TopCat.Presheaf.EtaleSpace
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[]
Etale space of a presheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
eventually_nhds (g : EtaleSpace F) {U : Opens X} (h : g.base ∈ U) (s : ToType (F.obj (op U))) (hs : F.germ U g.base h s = g.germ) : ∀ᶠ g' : EtaleSpace F in 𝓝 g, ∃ hgU : g'.base ∈ U, g'.germ = F.germ U g'.base hgU s
by simp only [nhds_generateFrom, Filter.Eventually, mem_setOf_eq, iInf_and, iInf_exists] refine mem_iInf_of_mem _ <| mem_iInf_of_mem ?_ <| mem_iInf_of_mem U <| mem_iInf_of_mem s <| mem_iInf_of_mem rfl <| mem_principal_self _ simp [*]
theorem
TopCat.Presheaf.EtaleSpace.eventually_nhds
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[ "Filter.Eventually" ]
If `s` is a section of a presheaf `F` over `U` with germ at `g.base` equal to `g.germ`, then a neighborhood of `g` consists of germs of `s` at points `x ∈ U`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuous_base : Continuous (base (F := F))
by rw [continuous_iff_continuousAt] intro x rw [ContinuousAt, (nhds_basis_opens _).tendsto_right_iff] rintro U ⟨hxU, hUo⟩ lift U to Opens X using hUo rcases F.exists_le_germ_eq x.germ hxU with ⟨V, hVU, hxV, f, hf⟩ refine x.eventually_nhds hxV f hf |>.mono ?_ aesop
theorem
TopCat.Presheaf.EtaleSpace.continuous_base
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[ "Continuous", "ContinuousAt", "continuous_iff_continuousAt", "nhds_basis_opens" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
exists_section_of_tendsto {α : Type*} {l : Filter α} {g : α → F.EtaleSpace} {g₀ : F.EtaleSpace} (h : Tendsto g l (𝓝 g₀)) : ∃ (U : Opens X), g₀.base ∈ U ∧ ∃ (f : ToType (F.obj (op U))), ∀ᶠ a in l, ∃ ha : (g a).base ∈ U, (g a).germ = F.germ U (g a).base ha f
by rcases F.exists_germ_eq g₀.germ with ⟨U, hU, s, hs⟩ use U, hU, s exact h.eventually <| g₀.eventually_nhds hU s hs
theorem
TopCat.Presheaf.EtaleSpace.exists_section_of_tendsto
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[ "Filter" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
homeomorph (U : Opens X) (hF_bij : ∀ (x : X) (hx : x ∈ U), Bijective (F.germ U x hx)) (x : X) (hx : x ∈ U) : (base (F := F) ⁻¹' U) ≃ₜ U × WithDiscreteTopology (ToType (F.stalk x))
where toFun s := (⟨s.1.base, s.2⟩, .toTopology ⊥ <| F.germ U x hx <| surjInv (hF_bij s.1.base s.2).surjective s.1.germ) invFun | (⟨y, hy⟩, .toTopology _ g) => ⟨⟨y, F.germ U y hy <| surjInv (hF_bij x hx).surjective g⟩, hy⟩ left_inv := by rintro ⟨⟨base, s⟩, hs⟩ simp only congr 2 rw [leftInvers...
def
TopCat.Presheaf.EtaleSpace.homeomorph
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[ "ContinuousAt", "WithDiscreteTopology", "continuousAt_prod_of_discrete_right", "continuous_iff_continuousAt", "continuous_subtype_val", "nhds_discrete", "nhds_subtype", "nhds_subtype_eq_comap" ]
Let `F` be a `C`-valued presheaf on `X`. Let `U` be an open set on `X` such that for each `x ∈ U`, the `germ` map is bijective, i.e., every germ can be extended to a unique section over `U`. Then for each `x ∈ U`, the preimage of `U` under `EtaleSpace.base` is homeomorphic to the product of `U` and the stalk of `F` at...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isCoveringMap_base (hF_bij : ∀ x, ∃ (U : Opens X), x ∈ U ∧ ∀ y (hyU : y ∈ U), Bijective (F.germ U y hyU)) : IsCoveringMap (base (F := F))
by refine fun x ↦ .to_isEvenlyCovered_preimage (I := WithDiscreteTopology (ToType (F.stalk x))) ?_ use inferInstance rcases hF_bij x with ⟨U, hxU, hU_bij⟩ use U, hxU, U.isOpen, U.isOpen.preimage (continuous_base F), homeomorph U hU_bij x hxU simp
theorem
TopCat.Presheaf.EtaleSpace.isCoveringMap_base
Topology.Sheaves
Mathlib/Topology/Sheaves/EtaleSpace.lean
[]
[ "IsCoveringMap", "WithDiscreteTopology" ]
Let `F` be a presheaf with the following property. For each `x`, there exists an open neighborhood `U ∋ x` such that for each `y ∈ U`, the map `Presheaf.germ F U y hyU` from sections of `F` over `U` to the stalk at `y` is bijective. Then the projection from the etale space of `F` to the base is a covering map.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
IsFlasque : Prop where epi : ∀ {U V : (Opens X)ᵒᵖ} (i : U ⟶ V), Epi (F.map i)
class
TopCat.Presheaf.IsFlasque
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[]
A sheaf is flasque if all of the restriction morphisms are epimorphisms.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_isFlasque {Y : TopCat.{u}} [IsFlasque F] (f : X ⟶ Y) : IsFlasque (f _* F)
where epi {U V} i := by simp only [pushforward_obj_obj, pushforward_obj_map] infer_instance
instance
TopCat.Presheaf.IsFlasque.pushforward_isFlasque
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
IsFlasque {C : Type v} [Category.{w} C] (F : Sheaf C X)
Presheaf.IsFlasque F.obj
abbrev
TopCat.Sheaf.IsFlasque
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[]
A sheaf is flasque if it is flasque as a presheaf
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_isFlasque {C : Type v} [Category.{w} C] {Y : TopCat.{u}} (F : Sheaf C X) [IsFlasque F] (f : X ⟶ Y) : IsFlasque ((pushforward C f).obj F)
Presheaf.IsFlasque.pushforward_isFlasque F.1 f
instance
TopCat.Sheaf.IsFlasque.pushforward_isFlasque
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
Under
StructuredArrow ⟨op U, s⟩ (Functor.whiskerRight g.hom (CategoryTheory.forget AddCommGrpCat.{u})).mapElements
abbrev
TopCat.Sheaf.IsFlasque.Under
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "CategoryTheory.forget" ]
Given a morphism of sheaves `g: F ⟶ G` and a section `s` of `G(U)`, `Under g s` is comprised of an open `V` and a section of `F(V)` that maps to `s |_ V` via `g`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
structured_arrows_elements_sheaf_chains_bounded (c : Set (Under g s)) (h : IsChain (fun x y ↦ Nonempty (y ⟶ x)) c) : ∃ ub, ∀ a ∈ c, Nonempty (ub ⟶ a)
by let f : c → (Opens X) := fun x => x.1.right.1.unop obtain ⟨t, ht, _⟩ : ∃! s_1, IsGluing F.obj f (fun x => x.val.right.2) s_1 := by refine Sheaf.existsUnique_gluing F _ _ (fun i j ↦ ?_) obtain (rfl | h₁ | h₁) : i = j ∨ Nonempty (i.val ⟶ j.val) ∨ Nonempty (j.val ⟶ i.val) := by grind [Subtype.ext_iff,...
lemma
TopCat.Sheaf.IsFlasque.structured_arrows_elements_sheaf_chains_bounded
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "AddCommGrpCat", "CategoryTheory.forget", "IsChain", "Set", "iSup", "iSup_le", "le_iSup", "symm" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
epi_of_shortExact {S : ShortComplex (Sheaf AddCommGrpCat X)} (hS : S.ShortExact) [IsFlasque S.X₁] : Epi (S.g.1.app (op U))
by refine (AddCommGrpCat.epi_iff_surjective _).mpr (fun s ↦ ?_) -- We want to find a preimage of `s` by `S.g`. -- We apply Zorn's lemma to obtain a term `t` of `Under S.g s` that is maximal. obtain ⟨t, ht⟩ := exists_maximal_of_chains_bounded (structured_arrows_elements_sheaf_chains_bounded S.g s) (fun ⟨...
theorem
TopCat.Sheaf.IsFlasque.epi_of_shortExact
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "AddCommGrpCat", "CategoryTheory.comp_apply", "CategoryTheory.forget", "exists_maximal_of_chains_bounded", "iSup", "le_iSup", "le_of_eq", "symm" ]
Given a short exact sequence of sheaves, `0 ⟶ 𝓕 ⟶ 𝓖 ⟶ 𝓗 ⟶ 0`, if `𝓕` is flasque then `𝓖(U) ⟶ 𝓗(U)` is surjective, for any open `U`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
of_shortExact_of_isFlasque₁₂ {S : ShortComplex (Sheaf AddCommGrpCat X)} (hS : S.ShortExact) [IsFlasque S.X₁] [IsFlasque S.X₂] : IsFlasque S.X₃
where epi {U V} i := by have : Epi (S.g.1.app U ≫ S.X₃.obj.map i) := by rw [← S.g.hom.naturality i] exact CategoryTheory.epi_comp' inferInstance (epi_of_shortExact hS) exact CategoryTheory.epi_of_epi (S.g.1.app U) (S.X₃.obj.map i)
theorem
TopCat.Sheaf.IsFlasque.of_shortExact_of_isFlasque₁₂
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "AddCommGrpCat", "CategoryTheory.epi_comp'", "CategoryTheory.epi_of_epi" ]
Given a short exact sequence of sheaves, `0 ⟶ 𝓕 ⟶ 𝓖 ⟶ 𝓗 ⟶ 0`, if `𝓕` and `𝓖` are flasque, then `𝓗` is flasque.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isFlasque_skyscraperSheaf_of_epi_from {X : TopCat} (p₀ : ↑X) [(U : Opens ↑X) → Decidable (p₀ ∈ U)] {C : Type*} [Category* C] (A : C) [HasTerminal C] [Epi <| terminalIsTerminal.from A] : (skyscraperSheaf p₀ A).IsFlasque
where epi {U V} r := by by_cases h1 : p₀ ∈ unop U · by_cases h2 : p₀ ∈ unop V · simp_all only [skyscraperSheaf_obj_obj, skyscraperSheaf_obj_map, ↓reduceDIte] infer_instance · simp grind · have h2 : p₀ ∉ unop V := fun hV => h1 (r.unop.le hV) have := isIso_of_isTerminal (is...
theorem
TopCat.Sheaf.isFlasque_skyscraperSheaf_of_epi_from
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "TopCat", "by_cases", "isTerminalSkyscraperSheafObjObjOfNotMem", "skyscraperSheaf" ]
If the unique map from `A` to the terminal object is an epimorphism, then the skyscraper sheaf valued in `A` supported at an arbitrary point is a flasque sheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isFlasque_skyscraperSheaf_of_hasZeroObject {X : TopCat} (p₀ : ↑X) [(U : Opens ↑X) → Decidable (p₀ ∈ U)] {C : Type*} [Category* C] (A : C) [HasZeroObject C] : (skyscraperSheaf p₀ A).IsFlasque
isFlasque_skyscraperSheaf_of_epi_from p₀ A
theorem
TopCat.Sheaf.isFlasque_skyscraperSheaf_of_hasZeroObject
Topology.Sheaves
Mathlib/Topology/Sheaves/Flasque.lean
[]
[ "TopCat", "skyscraperSheaf" ]
If the target category has a zero object, then any skyscraper sheaf valued in this category is a flasque sheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isSheaf_iff_isSheaf_comp' {C : Type u₁} [Category.{v₁} C] {D : Type u₂} [Category.{v₂} D] (G : C ⥤ D) [G.ReflectsIsomorphisms] [HasLimitsOfSize.{v, v} C] [PreservesLimitsOfSize.{v, v} G] {X : TopCat.{v}} (F : Presheaf C X) : Presheaf.IsSheaf F ↔ Presheaf.IsSheaf (F ⋙ G)
Presheaf.isSheaf_iff_isSheaf_comp _ F G
theorem
TopCat.Presheaf.isSheaf_iff_isSheaf_comp'
Topology.Sheaves
Mathlib/Topology/Sheaves/Forget.lean
[]
[]
If `G : C ⥤ D` is a functor which reflects isomorphisms and preserves limits (we assume all limits exist in `C`), then checking the sheaf condition for a presheaf `F : Presheaf C X` is equivalent to checking the sheaf condition for `F ⋙ G`. The important special case is when `C` is a concrete category with a forgetful...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isSheaf_iff_isSheaf_comp {C : Type u₁} [Category.{v} C] {D : Type u₂} [Category.{v} D] (G : C ⥤ D) [G.ReflectsIsomorphisms] [HasLimits C] [PreservesLimits G] {X : TopCat.{v}} (F : Presheaf C X) : Presheaf.IsSheaf F ↔ Presheaf.IsSheaf (F ⋙ G)
isSheaf_iff_isSheaf_comp' G F
theorem
TopCat.Presheaf.isSheaf_iff_isSheaf_comp
Topology.Sheaves
Mathlib/Topology/Sheaves/Forget.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_sheaf_of_sheaf {F : X.Presheaf C} (h : F.IsSheaf) : (f _* F).IsSheaf
(Opens.map f).op_comp_isSheaf _ _ ⟨_, h⟩
theorem
TopCat.Sheaf.pushforward_sheaf_of_sheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
The pushforward of a sheaf (by a continuous map) is a sheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward (f : X ⟶ Y) : X.Sheaf C ⥤ Y.Sheaf C
(Opens.map f).sheafPushforwardContinuous _ _ _
def
TopCat.Sheaf.pushforward
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
The pushforward functor.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_forget (f : X ⟶ Y) : pushforward C f ⋙ forget C Y = forget C X ⋙ Presheaf.pushforward C f
rfl
lemma
TopCat.Sheaf.pushforward_forget
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforwardForgetIso (f : X ⟶ Y) : pushforward C f ⋙ forget C Y ≅ forget C X ⋙ Presheaf.pushforward C f
Iso.refl _
def
TopCat.Sheaf.pushforwardForgetIso
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
Pushforward of sheaves is isomorphic (actually definitionally equal) to pushforward of presheaves.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_obj_val (f : X ⟶ Y) (F : X.Sheaf C) : ((pushforward C f).obj F).1 = f _* F.1
rfl
lemma
TopCat.Sheaf.pushforward_obj_val
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pushforward_map (f : X ⟶ Y) {F F' : X.Sheaf C} (α : F ⟶ F') : ((pushforward C f).map α).1 = (Presheaf.pushforward C f).map α.1
rfl
lemma
TopCat.Sheaf.pushforward_map
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pullback (f : X ⟶ Y) : Y.Sheaf A ⥤ X.Sheaf A
(Opens.map f).sheafPullback _ _ _
def
TopCat.Sheaf.pullback
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
The pullback functor.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pullbackIso (f : X ⟶ Y) : pullback A f ≅ forget A Y ⋙ Presheaf.pullback A f ⋙ presheafToSheaf _ _
Functor.sheafPullbackConstruction.sheafPullbackIso _ _ _ _
def
TopCat.Sheaf.pullbackIso
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
The pullback of a sheaf is isomorphic (actually definitionally equal) to the sheafification of the pullback as a presheaf.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
pullbackPushforwardAdjunction (f : X ⟶ Y) : pullback A f ⊣ pushforward A f
(Opens.map f).sheafAdjunctionContinuous _ _ _
def
TopCat.Sheaf.pullbackPushforwardAdjunction
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[]
The adjunction between pullback and pushforward for sheaves on topological spaces.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
sheafPullback : Y.Sheaf A ⥤ X.Sheaf A
haveI := Topology.IsOpenEmbedding.functor_isContinuous hf hf.functor.sheafPushforwardContinuous _ _ _
def
Topology.IsOpenEmbedding.sheafPullback
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[ "Topology.IsOpenEmbedding.functor_isContinuous" ]
The "naive" sheaf pullback by an open embedding `f`: on the underlying presheaf, this is just composition by the functor `IsOpenMap.functor f` (sending an open `U` to `f '' U`).
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
sheafPullbackIso : Sheaf.pullback A f ≅ hf.sheafPullback A
by refine Sheaf.pullbackIso A f ≪≫ NatIso.ofComponents (fun F ↦ ?_) (fun u ↦ ?_) · exact (presheafToSheaf (Opens.grothendieckTopology ↑X) A).mapIso (hf.isOpenMap.pullbackIso.app _) ≪≫ (fullyFaithfulSheafToPresheaf (Opens.grothendieckTopology X) A).preimageIso (isoSheafify (Opens.grothendieckTopolo...
def
Topology.IsOpenEmbedding.sheafPullbackIso
Topology.Sheaves
Mathlib/Topology/Sheaves/Functors.lean
[]
[ "CategoryTheory.sheafifyLift_comp", "Opens.grothendieckTopology", "TopCat.Presheaf.isSheaf_of_isOpenEmbedding", "symm" ]
The pullback of a sheaf by an open embedding `f` is isomorphic to its naive pullback `IsOpenEmbedding.sheafPullback`, i.e. to the composition by the functor `IsOpenMap.functor f`. Also, this is an isomorphism of functors.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isSheaf_of_isLimit [HasLimitsOfShape J C] {X : TopCat.{v}} (F : J ⥤ Presheaf.{v} C X) (H : ∀ j, (F.obj j).IsSheaf) {c : Cone F} (hc : IsLimit c) : c.pt.IsSheaf
by let F' : J ⥤ Sheaf C X := { obj := fun j => ⟨F.obj j, H j⟩ map := fun f => ⟨F.map f⟩ } let e : F' ⋙ Sheaf.forget C X ≅ F := NatIso.ofComponents fun _ => Iso.refl _ exact Presheaf.isSheaf_of_iso ((isLimitOfPreserves (Sheaf.forget C X) (limit.isLimit F')).conePointsIsoOfNatIso hc e) (limit F')....
theorem
TopCat.isSheaf_of_isLimit
Topology.Sheaves
Mathlib/Topology/Sheaves/Limits.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
limit_isSheaf [HasLimitsOfShape J C] {X : TopCat.{v}} (F : J ⥤ Presheaf.{v} C X) (H : ∀ j, (F.obj j).IsSheaf) : (limit F).IsSheaf
isSheaf_of_isLimit F H (limit.isLimit F)
theorem
TopCat.limit_isSheaf
Topology.Sheaves
Mathlib/Topology/Sheaves/Limits.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
IsLocallySurjective (T : ℱ ⟶ 𝒢)
CategoryTheory.Presheaf.IsLocallySurjective (Opens.grothendieckTopology X) T
def
TopCat.Presheaf.IsLocallySurjective
Topology.Sheaves
Mathlib/Topology/Sheaves/LocallySurjective.lean
[]
[ "CategoryTheory.Presheaf.IsLocallySurjective", "Opens.grothendieckTopology" ]
A map of presheaves `T : ℱ ⟶ 𝒢` is **locally surjective** if for any open set `U`, section `t` over `U`, and `x ∈ U`, there exists an open set `x ∈ V ⊆ U` and a section `s` over `V` such that `$T_*(s_V) = t|_V$`. See `TopCat.Presheaf.isLocallySurjective_iff` below.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
isLocallySurjective_iff (T : ℱ ⟶ 𝒢) : IsLocallySurjective T ↔ ∀ (U t), ∀ x ∈ U, ∃ (V : _) (_ : V ≤ U), (∃ s, (T.app _) s = t |_ V) ∧ x ∈ V
by refine ⟨fun h _ t x hx ↦ ?_, fun h => ⟨fun s x hx ↦ ?_⟩⟩ · obtain ⟨V, i, hi⟩ := h.imageSieve_mem t x hx exact ⟨V, leOfHom i, hi⟩ · obtain ⟨V, Vle, hV⟩ := h _ s x hx exact ⟨V, homOfLE Vle, hV⟩
theorem
TopCat.Presheaf.isLocallySurjective_iff
Topology.Sheaves
Mathlib/Topology/Sheaves/LocallySurjective.lean
[]
[]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
locally_surjective_iff_surjective_on_stalks (T : ℱ ⟶ 𝒢) : IsLocallySurjective T ↔ ∀ x : X, Function.Surjective ((stalkFunctor C x).map T)
by constructor <;> intro hT · /- human proof: Let g ∈ Γₛₜ 𝒢 x be a germ. Represent it on an open set U ⊆ X as ⟨t, U⟩. By local surjectivity, pass to a smaller open set V on which there exists s ∈ Γ_ ℱ V mapping to t |_ V. Then the germ of s maps to g -/ -- Let g ∈ Γₛₜ 𝒢 x be a ...
theorem
TopCat.Presheaf.locally_surjective_iff_surjective_on_stalks
Topology.Sheaves
Mathlib/Topology/Sheaves/LocallySurjective.lean
[]
[ "symm" ]
An equivalent condition for a map of presheaves to be locally surjective is for all the induced maps on stalks to be surjective.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
TopCat.Sheaf.isLocallySurjective_iff_epi {X : TopCat.{v}} {C : Type u} [Category.{v} C] {FC : C → C → Type*} {CC : C → Type v} [∀ X Y, FunLike (FC X Y) (CC X) (CC Y)] [ConcreteCategory C FC] [Balanced (CategoryTheory.Sheaf (Opens.grothendieckTopology X) C)] [(Opens.grothendieckTopology X).HasSheafCompose (C...
CategoryTheory.Sheaf.isLocallySurjective_iff_epi' ..
theorem
TopCat.Sheaf.isLocallySurjective_iff_epi
Topology.Sheaves
Mathlib/Topology/Sheaves/LocallySurjective.lean
[]
[ "Balanced", "CategoryTheory.Sheaf", "CategoryTheory.Sheaf.isLocallySurjective_iff_epi'", "CategoryTheory.forget", "FunLike", "Opens.grothendieckTopology", "TopCat.Presheaf.IsLocallySurjective" ]
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PrelocalPredicate where /-- The underlying predicate of a prelocal predicate -/ pred : ∀ {U : Opens X}, (∀ x : U, T x) → Prop /-- The underlying predicate should be invariant under restriction -/ res : ∀ {U V : Opens X} (i : U ⟶ V) (f : ∀ x : V, T x) (_ : pred f), pred fun x : U ↦ f (i x)
structure
TopCat.PrelocalPredicate
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[]
Given a topological space `X : TopCat` and a type family `T : X → Type`, a `P : PrelocalPredicate T` consists of: * a family of predicates `P.pred`, one for each `U : Opens X`, of the form `(Π x : U, T x) → Prop` * a proof that if `f : Π x : V, T x` satisfies the predicate on `V : Opens X`, then the restriction of `f...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuousPrelocal (T) [TopologicalSpace T] : PrelocalPredicate fun _ : X ↦ T
where pred {_} f := Continuous f res {_ _} i _ h := Continuous.comp h (Opens.isOpenEmbedding_of_le i.le).continuous
def
TopCat.continuousPrelocal
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[ "Continuous", "Continuous.comp", "TopologicalSpace" ]
Continuity is a "prelocal" predicate on functions to a fixed topological space `T`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
inhabitedPrelocalPredicate (T) [TopologicalSpace T] : Inhabited (PrelocalPredicate fun _ : X ↦ T)
⟨continuousPrelocal X T⟩
instance
TopCat.inhabitedPrelocalPredicate
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[ "TopologicalSpace" ]
Satisfying the inhabited linter.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
LocalPredicate extends PrelocalPredicate T where /-- A local predicate must be local --- provided that it is locally satisfied, it is also globally satisfied -/ locality : ∀ {U : Opens X} (f : ∀ x : U, T x) (_ : ∀ x : U, ∃ (V : Opens X) (_ : x.1 ∈ V) (i : V ⟶ U), pred fun x : V ↦ f (i x : U)), p...
structure
TopCat.LocalPredicate
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[]
Given a topological space `X : TopCat` and a type family `T : X → Type`, a `P : LocalPredicate T` consists of: * a family of predicates `P.pred`, one for each `U : Opens X`, of the form `(Π x : U, T x) → Prop` * a proof that if `f : Π x : V, T x` satisfies the predicate on `V : Opens X`, then the restriction of `f` t...
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
continuousLocal (T) [TopologicalSpace T] : LocalPredicate fun _ : X ↦ T
{ continuousPrelocal X T with locality := fun {U} f w ↦ by apply continuous_iff_continuousAt.2 intro x specialize w x rcases w with ⟨V, m, i, w⟩ dsimp at w rw [continuous_iff_continuousAt] at w specialize w ⟨x, m⟩ simpa using (Opens.isOpenEmbedding_of_le i.le).continu...
def
TopCat.continuousLocal
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[ "TopologicalSpace", "continuous_iff_continuousAt" ]
Continuity is a "local" predicate on functions to a fixed topological space `T`.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
inhabitedLocalPredicate (T) [TopologicalSpace T] : Inhabited (LocalPredicate fun _ : X ↦ T)
⟨continuousLocal X T⟩
instance
TopCat.inhabitedLocalPredicate
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[ "TopologicalSpace" ]
Satisfying the inhabited linter.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319
PrelocalPredicate.and (P Q : PrelocalPredicate T) : PrelocalPredicate T
where pred f := P.pred f ∧ Q.pred f res i f h := ⟨P.res i f h.1, Q.res i f h.2⟩
def
TopCat.PrelocalPredicate.and
Topology.Sheaves
Mathlib/Topology/Sheaves/LocalPredicate.lean
[]
[]
The conjunction of two prelocal predicates is prelocal.
https://github.com/leanprover-community/mathlib4
b9f14353520df73472ae3825fb53f86559a01319