mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.CategoryTheory.Sites.LocallyBijective

Goal state before:
pp: C : Type u
inst✝⁸ : Category.{v, u} C
J : GrothendieckTopology C
A : Type u'
inst✝⁷ : Category.{v', u'} A
FA : A → A → Type u_1
CA : A → Type w'
inst✝⁶ : (X Y : A) → FunLike (FA X Y) (CA X) (CA Y)
inst✝⁵ : ConcreteCategory A FA
inst✝⁴ : HasWeakSheafify J A
inst✝³ : (forget A).ReflectsIsomorphisms
inst✝² : J.HasSheafCompose (forget A)
inst✝¹ : ∀ (P : Cᵒᵖ ⥤ A), Presheaf.IsLocallyInjective J (CategoryTheory.toSheafify J P)
inst✝ : ∀ (P : Cᵒᵖ ⥤ A), Presheaf.IsLocallySurjective J (CategoryTheory.toSheafify J P)
P Q : Cᵒᵖ ⥤ A
f : P ⟶ Q
⊢ Sheaf.IsLocallyInjective ((presheafToSheaf J A).map f) ∧ Sheaf.IsLocallySurjective ((presheafToSheaf J A).map f) ↔
    Presheaf.IsLocallyInjective J (CategoryTheory.sheafifyMap J f) ∧
      Presheaf.IsLocallySurjective J (CategoryTheory.toSheafify J P ≫ CategoryTheory.sheafifyMap J f)

Tactic:
Presheaf.comp_isLocallySurjective_iff

Goal state after:
C : Type u
inst✝⁸ : Category.{v, u} C
J : GrothendieckTopology C
A : Type u'
inst✝⁷ : Category.{v', u'} A
FA : A → A → Type u_1
CA : A → Type w'
inst✝⁶ : (X Y : A) → FunLike (FA X Y) (CA X) (CA Y)
inst✝⁵ : ConcreteCategory A FA
inst✝⁴ : HasWeakSheafify J A
inst✝³ : (forget A).ReflectsIsomorphisms
inst✝² : J.HasSheafCompose (forget A)
inst✝¹ : ∀ (P : Cᵒᵖ ⥤ A), Presheaf.IsLocallyInjective J (CategoryTheory.toSheafify J P)
inst✝ : ∀ (P : Cᵒᵖ ⥤ A), Presheaf.IsLocallySurjective J (CategoryTheory.toSheafify J P)
P Q : Cᵒᵖ ⥤ A
f : P ⟶ Q
⊢ Sheaf.IsLocallyInjective ((presheafToSheaf J A).map f) ∧ Sheaf.IsLocallySurjective ((presheafToSheaf J A).map f) ↔
    Presheaf.IsLocallyInjective J (CategoryTheory.sheafifyMap J f) ∧
      Presheaf.IsLocallySurjective J (CategoryTheory.sheafifyMap J f)
Module: Mathlib.CategoryTheory.Sites.LocallySurjective

Goal state before:
pp: C : Type u
inst✝⁵ : Category.{v, u} C
J : GrothendieckTopology C
A : Type u'
inst✝⁴ : Category.{v', u'} A
FA : A → A → Type u_1
CA : A → Type w'
inst✝³ : (X Y : A) → FunLike (FA X Y) (CA X) (CA Y)
inst✝² : ConcreteCategory A FA
F₁ F₂ F₃ : Cᵒᵖ ⥤ A
f₁ : F₁ ⟶ F₂
f₂ : F₂ ⟶ F₃
f₃ : F₁ ⟶ F₃
fac : f₁ ≫ f₂ = f₃
inst✝¹ : IsLocallySurjective J f₃
inst✝ : IsLocallyInjective J f₂
⊢ IsLocallySurjective J f₁

Tactic:
subst fac
  exact isLocallySurjective_of_isLocallySurjective_of_isLocallyInjective J f₁ f₂

Goal state after:
Module: Mathlib.CategoryTheory.Limits.Bicones

Goal state before:
pp: case left.diagram
J : Type u₁
inst✝ : Category.{v₁, u₁} J
j✝ k✝ : J
f✝ : j✝ ⟶ k✝
⊢ BiconeHom J Bicone.left (Bicone.diagram k✝)

Tactic:
apply BiconeHom.left

Goal state after:
Module: Mathlib.CategoryTheory.Sites.Hypercover.Zero

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
S T : C
E : PreZeroHypercover S
F✝ F : PreZeroHypercover S
G : PreZeroHypercover S
inst✝ : ∀ (i : E.I₀) (j : F.I₀), HasPullback (E.f i) (F.f j)
i : (E.inter F).I₀
⊢ pullback.snd (E.f ((Equiv.sigmaEquivProd E.I₀ F.1).symm i).fst) (F.f ((Equiv.sigmaEquivProd E.I₀ F.1).symm i).snd) ≫
      F.f i.2 =
    (E.inter F).f i

Tactic:
simp [← pullback.condition]

Goal state after:
Module: Mathlib.CategoryTheory.Sites.Hypercover.IsSheaf

Goal state before:
pp: C : Type u
inst✝² : Category.{v, u} C
J : GrothendieckTopology C
A : Type u'
inst✝¹ : Category.{v', u'} A
inst✝ : J.IsGeneratedByOneHypercovers
P : Cᵒᵖ ⥤ A
⊢ IsSheaf J P ↔ ∀ ⦃X : C⦄ (E : J.OneHypercover X), Nonempty (IsLimit (E.multifork P))

Tactic:
simpa using GrothendieckTopology.OneHypercoverFamily.isSheaf_iff.{w} ⊤ P

Goal state after:
Module: Mathlib.CategoryTheory.Sites.Continuous

Goal state before:
pp: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
D : Type u₂
inst✝² : Category.{v₂, u₂} D
X : C
E : PreOneHypercover X
F : C ⥤ D
i₁ i₂ : E.I₀
inst✝¹ : HasPullback (E.f i₁) (E.f i₂)
inst✝ : PreservesLimit (cospan (E.f i₁) (E.f i₂)) F
⊢ Sieve.functorPushforward F (E.sieve₁' i₁ i₂) =
    (E.map F).sieve₁ (F.map (pullback.fst (E.f i₁) (E.f i₂))) (F.map (pullback.snd (E.f i₁) (E.f i₂)))

Tactic:
have : HasPullback ((E.map F).f i₁) ((E.map F).f i₂) :=
    hasPullback_of_preservesPullback F (E.f i₁) (E.f i₂)

Goal state after:
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
D : Type u₂
inst✝² : Category.{v₂, u₂} D
X : C
E : PreOneHypercover X
F : C ⥤ D
i₁ i₂ : E.I₀
inst✝¹ : HasPullback (E.f i₁) (E.f i₂)
inst✝ : PreservesLimit (cospan (E.f i₁) (E.f i₂)) F
this : HasPullback ((E.map F).f i₁) ((E.map F).f i₂)
⊢ Sieve.functorPushforward F (E.sieve₁' i₁ i₂) =
    (E.map F).sieve₁ (F.map (pullback.fst (E.f i₁) (E.f i₂))) (F.map (pullback.snd (E.f i₁) (E.f i₂)))
Module: Mathlib.CategoryTheory.Sites.Continuous

Goal state before:
pp: C : Type u₁
inst✝³ : Category.{v₁, u₁} C
D : Type u₂
inst✝² : Category.{v₂, u₂} D
X : C
E : PreOneHypercover X
F : C ⥤ D
W : C
i₁ i₂ : E.I₀
p₁ : W ⟶ E.X i₁
p₂ : W ⟶ E.X i₂
h : p₁ ≫ E.f i₁ = p₂ ≫ E.f i₂
inst✝¹ : HasPullbacks C
inst✝ : PreservesLimitsOfShape WalkingCospan F
⊢ (E.map F).sieve₁ (F.map p₁) (F.map p₂) ≤ Sieve.functorPushforward F (E.sieve₁ p₁ p₂)

Tactic:
have : HasPullback ((E.map F).f i₁) ((E.map F).f i₂) :=
    hasPullback_of_preservesPullback F (E.f i₁) (E.f i₂)

Goal state after:
C : Type u₁
inst✝³ : Category.{v₁, u₁} C
D : Type u₂
inst✝² : Category.{v₂, u₂} D
X : C
E : PreOneHypercover X
F : C ⥤ D
W : C
i₁ i₂ : E.I₀
p₁ : W ⟶ E.X i₁
p₂ : W ⟶ E.X i₂
h : p₁ ≫ E.f i₁ = p₂ ≫ E.f i₂
inst✝¹ : HasPullbacks C
inst✝ : PreservesLimitsOfShape WalkingCospan F
this : HasPullback ((E.map F).f i₁) ((E.map F).f i₂)
⊢ (E.map F).sieve₁ (F.map p₁) (F.map p₂) ≤ Sieve.functorPushforward F (E.sieve₁ p₁ p₂)
Module: Mathlib.CategoryTheory.Sites.CoverPreserving

Goal state before:
pp: C : Type u₁
inst✝² : Category.{v₁, u₁} C
D : Type u₂
inst✝¹ : Category.{v₂, u₂} D
K : GrothendieckTopology D
G : C ⥤ D
inst✝ : RepresentablyFlat G
ℱ : Sheaf K (Type u_1)
Z : C
T : Presieve Z
x : FamilyOfElements (G.op ⋙ ℱ.obj) T
hx : x.Compatible
Y₁ Y₂ : C
X : D
f₁ : X ⟶ G.obj Y₁
f₂ : X ⟶ G.obj Y₂
g₁ : Y₁ ⟶ Z
g₂ : Y₂ ⟶ Z
hg₁ : T g₁
hg₂ : T g₂
e : f₁ ≫ G.map g₁ = f₂ ≫ G.map g₂
c : Cone (cospan g₁ g₂ ⋙ G) :=
  (Cone.postcompose (diagramIsoCospan (cospan g₁ g₂ ⋙ G)).inv).obj (PullbackCone.mk f₁ f₂ e)
⊢ (ConcreteCategory.hom (ℱ.obj.map f₁.op)) (x g₁ hg₁) = (ConcreteCategory.hom (ℱ.obj.map f₂.op)) (x g₂ hg₂)

Tactic:
let c' := IsCofiltered.cone (c.toStructuredArrow ⋙ StructuredArrow.pre _ _ _)

Goal state after:
C : Type u₁
inst✝² : Category.{v₁, u₁} C
D : Type u₂
inst✝¹ : Category.{v₂, u₂} D
K : GrothendieckTopology D
G : C ⥤ D
inst✝ : RepresentablyFlat G
ℱ : Sheaf K (Type u_1)
Z : C
T : Presieve Z
x : FamilyOfElements (G.op ⋙ ℱ.obj) T
hx : x.Compatible
Y₁ Y₂ : C
X : D
f₁ : X ⟶ G.obj Y₁
f₂ : X ⟶ G.obj Y₂
g₁ : Y₁ ⟶ Z
g₂ : Y₂ ⟶ Z
hg₁ : T g₁
hg₂ : T g₂
e : f₁ ≫ G.map g₁ = f₂ ≫ G.map g₂
c : Cone (cospan g₁ g₂ ⋙ G) :=
  (Cone.postcompose (diagramIsoCospan (cospan g₁ g₂ ⋙ G)).inv).obj (PullbackCone.mk f₁ f₂ e)
c' : Cone (c.toStructuredArrow ⋙ StructuredArrow.pre c.pt (cospan g₁ g₂) G) :=
  IsCofiltered.cone (c.toStructuredArrow ⋙ StructuredArrow.pre c.pt (cospan g₁ g₂) G)
⊢ (ConcreteCategory.hom (ℱ.obj.map f₁.op)) (x g₁ hg₁) = (ConcreteCategory.hom (ℱ.obj.map f₂.op)) (x g₂ hg₂)
Module: Mathlib.CategoryTheory.Sites.Hypercover.One

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E : PreOneHypercover S
F : Cᵒᵖ ⥤ A
⊢ ∀ (b : E.multicospanShape.R),
    F.map (E.f (E.multicospanShape.fst b)).op ≫ (E.multicospanIndex F).fst b =
      F.map (E.f (E.multicospanShape.snd b)).op ≫ (E.multicospanIndex F).snd b

Tactic:
by
    rintro ⟨⟨i₁, i₂⟩, (j : E.I₁ i₁ i₂)⟩
    dsimp
    simp only [← F.map_comp, ← op_comp, E.w]

Goal state after:
Module: Mathlib.CategoryTheory.Sites.DenseSubsite.Basic

Goal state before:
pp: C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
D : Type u_2
inst✝³ : Category.{v_2, u_2} D
E : Type u_3
inst✝² : Category.{v_3, u_3} E
J : GrothendieckTopology C
K : GrothendieckTopology D
L : GrothendieckTopology E
G : C ⥤ D
A : Type u_4
inst✝¹ : Category.{v_4, u_4} A
inst✝ : IsDenseSubsite J K G
F : Sheaf J A
X Y : C
f : G.obj X ⟶ G.obj Y
W₀ : C
a : W₀ ⟶ X
ha : (↑⟨G.imageSieve f, ⋯⟩).arrows a
W₀' : C
a' : W₀' ⟶ X
ha' : (↑⟨G.imageSieve f, ⋯⟩).arrows a'
T₀ : C
p₁ : T₀ ⟶ { Y := W₀, f := a, hf := ha }.Y
p₂ : T₀ ⟶ { Y := W₀', f := a', hf := ha' }.Y
fac : p₁ ≫ { Y := W₀, f := a, hf := ha }.f = p₂ ≫ { Y := W₀', f := a', hf := ha' }.f
⊢ G.map ({ Z := T₀, g₁ := p₁, g₂ := p₂, w := fac }.g₁ ≫ Exists.choose ha) =
    G.map ({ Z := T₀, g₁ := p₁, g₂ := p₂, w := fac }.g₂ ≫ Exists.choose ha')

Tactic:
rw [Functor.map_comp, Functor.map_comp, ha.choose_spec, ha'.choose_spec,
        ← Functor.map_comp_assoc, ← Functor.map_comp_assoc, fac]

Goal state after:
Module: Mathlib.CategoryTheory.Sites.DenseSubsite.InducedTopology

Goal state before:
pp: case mp
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
D : Type u_2
inst✝³ : Category.{v_2, u_2} D
G : C ⥤ D
K : GrothendieckTopology D
inst✝² : G.LocallyCoverDense K
inst✝¹ : G.Full
inst✝ : G.Faithful
X : C
S : Sieve X
⊢ Sieve.functorPushforward G S ∈ K (G.obj X) → ∃ T, Sieve.functorPullback G ↑T = S

pp: case mpr
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
D : Type u_2
inst✝³ : Category.{v_2, u_2} D
G : C ⥤ D
K : GrothendieckTopology D
inst✝² : G.LocallyCoverDense K
inst✝¹ : G.Full
inst✝ : G.Faithful
X : C
S : Sieve X
⊢ (∃ T, Sieve.functorPullback G ↑T = S) → Sieve.functorPushforward G S ∈ K (G.obj X)

Tactic:
· intro hS
    exact ⟨⟨_, hS⟩, (Sieve.fullyFaithfulFunctorGaloisCoinsertion G X).u_l_eq S⟩

Goal state after:
case mpr
C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
D : Type u_2
inst✝³ : Category.{v_2, u_2} D
G : C ⥤ D
K : GrothendieckTopology D
inst✝² : G.LocallyCoverDense K
inst✝¹ : G.Full
inst✝ : G.Faithful
X : C
S : Sieve X
⊢ (∃ T, Sieve.functorPullback G ↑T = S) → Sieve.functorPushforward G S ∈ K (G.obj X)
Module: Mathlib.CategoryTheory.Sites.PreservesLocallyBijective

Goal state before:
pp: C : Type u_1
D : Type u_2
A : Type u_3
inst✝⁶ : Category.{v_1, u_1} C
inst✝⁵ : Category.{v_2, u_2} D
inst✝⁴ : Category.{v_3, u_3} A
J : GrothendieckTopology C
K : GrothendieckTopology D
H : C ⥤ D
F G : Dᵒᵖ ⥤ A
f : F ⟶ G
FA : A → A → Type u_4
CA : A → Type u_5
inst✝³ : (X Y : A) → FunLike (FA X Y) (CA X) (CA Y)
inst✝² : ConcreteCategory A FA
hH : CoverPreserving J K H
inst✝¹ : H.IsCoverDense K
inst✝ : IsLocallySurjective J (H.op.whiskerLeft f)
X : D
a : ToType (G.obj (Opposite.op X))
Y : D
g : Y ⟶ X
Z : C
lift : Y ⟶ H.obj Z
m : H.obj Z ⟶ X
fac : lift ≫ m = g
hh :
  Sieve.functorPushforward H (imageSieve (H.op.whiskerLeft f) ((ConcreteCategory.hom (G.map m.op)) a)) ∈
    K (H.obj (Opposite.unop (Opposite.op Z)))
W : C
q : W ⟶ Z
x : ToType ((H.op ⋙ F).obj (Opposite.op W))
h :
  (ConcreteCategory.hom ((H.op.whiskerLeft f).app (Opposite.op W))) x =
    (ConcreteCategory.hom ((H.op ⋙ G).map q.op)) ((ConcreteCategory.hom (G.map m.op)) a)
⊢ (Sieve.functorPullback H (Sieve.pullback m (imageSieve f a))).arrows q

Tactic:
simp only [Sieve.functorPullback_apply, Presieve.functorPullback_mem, Sieve.pullback_apply]

Goal state after:
C : Type u_1
D : Type u_2
A : Type u_3
inst✝⁶ : Category.{v_1, u_1} C
inst✝⁵ : Category.{v_2, u_2} D
inst✝⁴ : Category.{v_3, u_3} A
J : GrothendieckTopology C
K : GrothendieckTopology D
H : C ⥤ D
F G : Dᵒᵖ ⥤ A
f : F ⟶ G
FA : A → A → Type u_4
CA : A → Type u_5
inst✝³ : (X Y : A) → FunLike (FA X Y) (CA X) (CA Y)
inst✝² : ConcreteCategory A FA
hH : CoverPreserving J K H
inst✝¹ : H.IsCoverDense K
inst✝ : IsLocallySurjective J (H.op.whiskerLeft f)
X : D
a : ToType (G.obj (Opposite.op X))
Y : D
g : Y ⟶ X
Z : C
lift : Y ⟶ H.obj Z
m : H.obj Z ⟶ X
fac : lift ≫ m = g
hh :
  Sieve.functorPushforward H (imageSieve (H.op.whiskerLeft f) ((ConcreteCategory.hom (G.map m.op)) a)) ∈
    K (H.obj (Opposite.unop (Opposite.op Z)))
W : C
q : W ⟶ Z
x : ToType ((H.op ⋙ F).obj (Opposite.op W))
h :
  (ConcreteCategory.hom ((H.op.whiskerLeft f).app (Opposite.op W))) x =
    (ConcreteCategory.hom ((H.op ⋙ G).map q.op)) ((ConcreteCategory.hom (G.map m.op)) a)
⊢ (imageSieve f a).arrows (H.map q ≫ m)
Module: Mathlib.CategoryTheory.Sites.Equivalence

Goal state before:
pp: C : Type u₁
inst✝⁶ : Category.{v₁, u₁} C
J : GrothendieckTopology C
D : Type u₂
inst✝⁵ : Category.{v₂, u₂} D
K : GrothendieckTopology D
G : D ⥤ C
A : Type u₃
inst✝⁴ : Category.{v₃, u₃} A
inst✝³ : G.IsCoverDense J
inst✝² : G.Full
inst✝¹ : G.IsContinuous K J
inst✝ : (G.sheafPushforwardContinuous A K J).EssSurj
P Q : Cᵒᵖ ⥤ A
f : P ⟶ Q
⊢ (ObjectProperty.isoClosure fun x ↦ x ∈ Set.range (sheafToPresheaf K A).obj).isLocal =
    ObjectProperty.isLocal fun x ↦ x ∈ Set.range (sheafToPresheaf J A ⋙ (whiskeringLeft Dᵒᵖ Cᵒᵖ A).obj G.op).obj

Tactic:
conv_rhs => rw [← ObjectProperty.isoClosure_isLocal]

Goal state after:
C : Type u₁
inst✝⁶ : Category.{v₁, u₁} C
J : GrothendieckTopology C
D : Type u₂
inst✝⁵ : Category.{v₂, u₂} D
K : GrothendieckTopology D
G : D ⥤ C
A : Type u₃
inst✝⁴ : Category.{v₃, u₃} A
inst✝³ : G.IsCoverDense J
inst✝² : G.Full
inst✝¹ : G.IsContinuous K J
inst✝ : (G.sheafPushforwardContinuous A K J).EssSurj
P Q : Cᵒᵖ ⥤ A
f : P ⟶ Q
⊢ (ObjectProperty.isoClosure fun x ↦ x ∈ Set.range (sheafToPresheaf K A).obj).isLocal =
    (ObjectProperty.isoClosure fun x ↦
        x ∈ Set.range (sheafToPresheaf J A ⋙ (whiskeringLeft Dᵒᵖ Cᵒᵖ A).obj G.op).obj).isLocal
Module: Mathlib.CategoryTheory.Sites.Hypercover.One

Goal state before:
pp: case left
C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E✝¹ E✝ : PreOneHypercover S
F✝ : PreOneHypercover S
G : PreOneHypercover S
E F : PreOneHypercover S
f : E ≅ F
a✝ : E.multicospanShape.L
⊢ (Hom.mapMulticospan f.hom).map ((eqToIso ⋯).hom.app (WalkingMulticospan.left a✝)) ≫
      (eqToIso ⋯).hom.app ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.left a✝)) =
    𝟙 ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.left a✝))

Tactic:
eqToIso.hom,

Goal state after:
case left
C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E✝¹ E✝ : PreOneHypercover S
F✝ : PreOneHypercover S
G : PreOneHypercover S
E F : PreOneHypercover S
f : E ≅ F
a✝ : E.multicospanShape.L
⊢ (Hom.mapMulticospan f.hom).map ((eqToHom ⋯).app (WalkingMulticospan.left a✝)) ≫
      (eqToIso ⋯).hom.app ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.left a✝)) =
    𝟙 ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.left a✝))
Module: Mathlib.CategoryTheory.Sites.Hypercover.One

Goal state before:
pp: case right
C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E✝¹ E✝ : PreOneHypercover S
F✝ : PreOneHypercover S
G : PreOneHypercover S
E F : PreOneHypercover S
f : E ≅ F
a✝ : E.multicospanShape.R
⊢ (Hom.mapMulticospan f.hom).map ((eqToIso ⋯).hom.app (WalkingMulticospan.right a✝)) ≫
      (eqToIso ⋯).hom.app ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.right a✝)) =
    𝟙 ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.right a✝))

Tactic:
eqToIso.hom,

Goal state after:
case right
C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E✝¹ E✝ : PreOneHypercover S
F✝ : PreOneHypercover S
G : PreOneHypercover S
E F : PreOneHypercover S
f : E ≅ F
a✝ : E.multicospanShape.R
⊢ (Hom.mapMulticospan f.hom).map ((eqToHom ⋯).app (WalkingMulticospan.right a✝)) ≫
      (eqToIso ⋯).hom.app ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.right a✝)) =
    𝟙 ((Hom.mapMulticospan f.hom).obj (WalkingMulticospan.right a✝))
Module: Mathlib.CategoryTheory.Sites.Hypercover.One

Goal state before:
pp: case refine_2
C : Type u
inst✝¹ : Category.{v, u} C
A : Type u_1
inst✝ : Category.{v_1, u_1} A
S : C
E✝¹ E✝ : PreOneHypercover S
F✝ : PreOneHypercover S
G✝ : PreOneHypercover S
E F : PreOneHypercover S
f : E ≅ F
G : Cᵒᵖ ⥤ A
⊢ (Cone.postcompose
          (WalkingMulticospan.functorExt (fun i ↦ G.mapIso (asIso (f.hom.h₀ i)).symm.op)
              (fun i ↦ G.mapIso (asIso (f.hom.h₁ i.snd)).symm.op) ⋯ ⋯).hom).obj
      (E.multifork G) ≅
    Cone.whisker (equivalenceMulticospanOfIso f).functor (F.multifork G)

Tactic:
· refine Cone.ext (Iso.refl _) fun i ↦ ?_
    induction i with
    | left _ => simp [← Functor.map_comp, ← op_comp]
    | right _ => simp [← Functor.map_comp, ← op_comp, f.hom.w₁₁_assoc]

Goal state after:
Module: Mathlib.CategoryTheory.Sites.Over

Goal state before:
pp: case mpr
C : Type u
inst✝ : Category.{v, u} C
X : C
Y₁ Y₂ : Over X
f : Y₁ ⟶ Y₂
S : Sieve Y₂
Z : C
g : Z ⟶ Y₁.left
W : Over X
a : W ⟶ Y₂
b : Z ⟶ W.left
h : S.arrows a
w : g ≫ Over.Hom.left f = b ≫ Over.Hom.left a
T : Over X := Over.mk (b ≫ W.hom)
c : T ⟶ Y₁ := Over.homMk g ⋯
d : T ⟶ W := Over.homMk b ⋯
⊢ S.arrows (d ≫ a)

Tactic:
exact S.downward_closed h _

Goal state after:
Module: Mathlib.CategoryTheory.Sites.Over

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
X : C
Y : Over X
S : Sieve Y
Z : C
f : Z ⟶ Y.left
⊢ ((overEquiv Y) S).arrows f ↔ S.arrows (Over.homMk f ⋯)

Tactic:
obtain ⟨S, rfl⟩ := (overEquiv Y).symm.surjective S

Goal state after:
C : Type u
inst✝ : Category.{v, u} C
X : C
Y : Over X
Z : C
f : Z ⟶ Y.left
S : Sieve Y.left
⊢ ((overEquiv Y) ((overEquiv Y).symm S)).arrows f ↔ ((overEquiv Y).symm S).arrows (Over.homMk f ⋯)
Module: Mathlib.CategoryTheory.Sites.Over

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
X Y : C
f : X ⟶ Y
U : Over X
S : Sieve ((Over.map f).obj U)
Z : C
g : Z ⟶ U.left
u : (Over.map f).obj (Over.mk (g ≫ U.hom)) ⟶ Over.mk (g ≫ U.hom ≫ f) := Over.homMk (𝟙 Z) ⋯
heq : (Over.map f).map (Over.homMk g ⋯) = u ≫ Over.homMk g ⋯
this : IsIso u
⊢ ((overEquiv U) (functorPullback (Over.map f) S)).arrows g ↔ ((overEquiv ((Over.map f).obj U)) S).arrows g

Tactic:
Sieve.overEquiv_iff,

Goal state after:
C : Type u
inst✝ : Category.{v, u} C
X Y : C
f : X ⟶ Y
U : Over X
S : Sieve ((Over.map f).obj U)
Z : C
g : Z ⟶ U.left
u : (Over.map f).obj (Over.mk (g ≫ U.hom)) ⟶ Over.mk (g ≫ U.hom ≫ f) := Over.homMk (𝟙 Z) ⋯
heq : (Over.map f).map (Over.homMk g ⋯) = u ≫ Over.homMk g ⋯
this : IsIso u
⊢ (functorPullback (Over.map f) S).arrows (Over.homMk g ⋯) ↔ ((overEquiv ((Over.map f).obj U)) S).arrows g
Module: Mathlib.CategoryTheory.Sites.Over

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
X Y : C
f : X ⟶ Y
F : Sheaf (J.over Y) (Type u_1)
Z : Over X
x✝ : Presieve Z
x : Presieve.FamilyOfElements ((Over.map f).op ⋙ F.obj) x✝
hx : x.Compatible
Y₁ Y₂ : Over X
W : Over Y
f₁ : W ⟶ (Over.map f).obj Y₁
f₂ : W ⟶ (Over.map f).obj Y₂
g₁ : Y₁ ⟶ Z
g₂ : Y₂ ⟶ Z
hg₁ : x✝ g₁
hg₂ : x✝ g₂
h : f₁ ≫ (Over.map f).map g₁ = f₂ ≫ (Over.map f).map g₂
W' : Over X := Over.mk (Over.Hom.left f₁ ≫ Y₁.hom)
g₁' : W' ⟶ Y₁ := Over.homMk (Over.Hom.left f₁) ⋯
g₂' : W' ⟶ Y₂ := Over.homMk (Over.Hom.left f₂) ⋯
⊢ (Iso.refl ((Over.map f).obj W').left).hom ≫ W.hom = ((Over.map f).obj W').hom

Tactic:
by simpa [W'] using! (Over.w f₁).symm

Goal state after:
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasZeroMorphisms C
X Y : C
inst✝¹ : Simple X
f : X ⟶ Y
inst✝ : HasKernel f
w : f ≠ 0
⊢ kernel.ι f = 0

Tactic:
by_contra h

Goal state after:
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasZeroMorphisms C
X Y : C
inst✝¹ : Simple X
f : X ⟶ Y
inst✝ : HasKernel f
w : f ≠ 0
h : ¬kernel.ι f = 0
⊢ False
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasZeroMorphisms C
X Y : C
inst✝¹ : Simple Y
f : X ⟶ Y
inst✝ : Mono f
w : IsIso f → False
⊢ f = 0

Tactic:
by_contra h

Goal state after:
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasZeroMorphisms C
X Y : C
inst✝¹ : Simple Y
f : X ⟶ Y
inst✝ : Mono f
w : IsIso f → False
h : ¬f = 0
⊢ False
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: case mp
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : Abelian C
X : C
h : ∀ {Z : C} (f : X ⟶ Z) [Epi f], IsIso f ↔ f ≠ 0
Y : C
f : Y ⟶ X
I : Mono f
a✝ : IsIso f
hx : cokernel.π f = 0
⊢ f ≠ 0

Tactic:
by_contra h

Goal state after:
case mp
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : Abelian C
X : C
h✝ : ∀ {Z : C} (f : X ⟶ Z) [Epi f], IsIso f ↔ f ≠ 0
Y : C
f : Y ⟶ X
I : Mono f
a✝ : IsIso f
hx : cokernel.π f = 0
h : f = 0
⊢ False
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
X Y : C
inst✝ : Simple Y
f : X ⟶ Y
w : f ≠ 0
⊢ cokernel.π f = 0

Tactic:
by_contra h

Goal state after:
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
X Y : C
inst✝ : Simple Y
f : X ⟶ Y
w : f ≠ 0
h : ¬cokernel.π f = 0
⊢ False
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
X Y : C
inst✝¹ : Simple X
f : X ⟶ Y
inst✝ : Epi f
w : IsIso f → False
⊢ f = 0

Tactic:
by_contra h

Goal state after:
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
X Y : C
inst✝¹ : Simple X
f : X ⟶ Y
inst✝ : Epi f
w : IsIso f → False
h : ¬f = 0
⊢ False
Module: Mathlib.CategoryTheory.Simple

Goal state before:
pp: C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : HasZeroMorphisms C
inst✝ : HasZeroObject C
X : C
⊢ Simple X → IsSimpleOrder (Subobject X)

Tactic:
intro h
    infer_instance

Goal state after:
Module: Mathlib.Topology.Sheaves.SheafCondition.PairwiseIntersections

Goal state before:
pp: case mp
C : Type u_1
inst✝ : Category.{v_1, u_1} C
X : TopCat
F : Sheaf C X
U V : Opens ↑X
s : PullbackCone (F.obj.map (homOfLE ⋯).op) (F.obj.map (homOfLE ⋯).op)
ι : ULift.{w, 0} WalkingPair → Opens ↑X := ⋯
x✝ : ↑X
⊢ x✝ ∈ ↑(U ⊔ V) → ∃ i, x✝ ∈ ↑(WalkingPair.casesOn i.down U V)

pp: case mpr
C : Type u_1
inst✝ : Category.{v_1, u_1} C
X : TopCat
F : Sheaf C X
U V : Opens ↑X
s : PullbackCone (F.obj.map (homOfLE ⋯).op) (F.obj.map (homOfLE ⋯).op)
ι : ULift.{w, 0} WalkingPair → Opens ↑X := ⋯
x✝ : ↑X
⊢ (∃ i, x✝ ∈ ↑(WalkingPair.casesOn i.down U V)) → x✝ ∈ ↑(U ⊔ V)

Tactic:
· rintro (h | h)
      exacts [⟨⟨WalkingPair.left⟩, h⟩, ⟨⟨WalkingPair.right⟩, h⟩]

Goal state after:
case mpr
C : Type u_1
inst✝ : Category.{v_1, u_1} C
X : TopCat
F : Sheaf C X
U V : Opens ↑X
s : PullbackCone (F.obj.map (homOfLE ⋯).op) (F.obj.map (homOfLE ⋯).op)
ι : ULift.{w, 0} WalkingPair → Opens ↑X := ⋯
x✝ : ↑X
⊢ (∃ i, x✝ ∈ ↑(WalkingPair.casesOn i.down U V)) → x✝ ∈ ↑(U ⊔ V)
Module: Mathlib.Topology.Sheaves.Stalks

Goal state before:
pp: C : Type u
inst✝⁶ : Category.{v, u} C
inst✝⁵ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁴ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝³ : PreservesFilteredColimits (forget C)
inst✝² : HasLimits C
inst✝¹ : PreservesLimits (forget C)
inst✝ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
hinj : ∀ x ∈ U, Function.Injective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.hom))
hsurj :
  ∀ (t : CC (G.obj.obj (op U))) (x : ↥U),
    ∃ V,
      ∃ (_ : ↑x ∈ V), ∃ iVU s, (ConcreteCategory.hom (f.hom.app (op V))) s = (ConcreteCategory.hom (G.obj.map iVU.op)) t
t : CC (G.obj.obj (op U))
⊢ ∃ a, (ConcreteCategory.hom (f.hom.app (op U))) a = t

Tactic:
choose V mV iVU sf heq using hsurj t

Goal state after:
C : Type u
inst✝⁶ : Category.{v, u} C
inst✝⁵ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁴ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝³ : PreservesFilteredColimits (forget C)
inst✝² : HasLimits C
inst✝¹ : PreservesLimits (forget C)
inst✝ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
hinj : ∀ x ∈ U, Function.Injective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.hom))
hsurj :
  ∀ (t : CC (G.obj.obj (op U))) (x : ↥U),
    ∃ V,
      ∃ (_ : ↑x ∈ V), ∃ iVU s, (ConcreteCategory.hom (f.hom.app (op V))) s = (ConcreteCategory.hom (G.obj.map iVU.op)) t
t : CC (G.obj.obj (op U))
V : ↥U → Opens ↑X
mV : ∀ (x : ↥U), ↑x ∈ V x
iVU : (x : ↥U) → V x ⟶ U
sf : (x : ↥U) → ToType (F.obj.obj (op (V x)))
heq : ∀ (x : ↥U), (ConcreteCategory.hom (f.hom.app (op (V x)))) (sf x) = (ConcreteCategory.hom (G.obj.map (iVU x).op)) t
⊢ ∃ a, (ConcreteCategory.hom (f.hom.app (op U))) a = t