-- Mathlib/Topology/Sheaves/Stalks.lean
theorem app_isIso_of_stalkFunctor_map_iso  {F G : Sheaf C X} (f : F ⟶ G) (U : Opens X)
    [∀ x : U, IsIso ((stalkFunctor C x.val).map f.1)] : IsIso (f.1.app (op U))

Proof state:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
x : ↑X
hx : x ∈ U
⊢ Function.Bijective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Tactic:
apply (isIso_iff_bijective _).mp

Result:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
x : ↑X
hx : x ∈ U
⊢ IsIso ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Proof state:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ ∀ x ∈ U, Function.Bijective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Tactic:
intro x hx

Result:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
x : ↑X
hx : x ∈ U
⊢ Function.Bijective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Proof state:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ IsIso ((forget C).map (f.val.app (op U)))

Tactic:
rw [isIso_iff_bijective]

Result:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ Function.Bijective ((forget C).map (f.val.app (op U)))

Proof state:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ IsIso (f.val.app (op U))

Tactic:
suffices IsIso ((forget C).map (f.1.app (op U))) by
  exact isIso_of_reflects_iso (f.1.app (op U)) (forget C)

Result:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ IsIso ((forget C).map (f.val.app (op U)))

Proof state:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ Function.Bijective ((forget C).map (f.val.app (op U)))

Tactic:
apply app_bijective_of_stalkFunctor_map_bijective

Result:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
⊢ ∀ x ∈ U, Function.Bijective ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Proof state:
case h
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
x : ↑X
hx : x ∈ U
⊢ IsIso ⇑(ConcreteCategory.hom ((stalkFunctor C x).map f.val))

Tactic:
exact Functor.map_isIso (forget C) ((stalkFunctor C (⟨x, hx⟩ : U).1).map f.1)

Result:
no goals

Proof state:
C : Type u
inst✝⁷ : Category.{v, u} C
inst✝⁶ : HasColimits C
X : TopCat
FC : C → C → Type u_1
CC : C → Type v
inst✝⁵ : (X Y : C) → FunLike (FC X Y) (CC X) (CC Y)
instCC : ConcreteCategory C FC
inst✝⁴ : PreservesFilteredColimits (forget C)
inst✝³ : HasLimits C
inst✝² : PreservesLimits (forget C)
inst✝¹ : (forget C).ReflectsIsomorphisms
F G : Sheaf C X
f : F ⟶ G
U : Opens ↑X
inst✝ : ∀ (x : ↥U), IsIso ((stalkFunctor C ↑x).map f.val)
this : IsIso ((forget C).map (f.val.app (op U)))
⊢ IsIso (f.val.app (op U))

Tactic:
exact isIso_of_reflects_iso (f.1.app (op U)) (forget C)

Result:
no goals