Theorem: CategoryTheory.GrothendieckTopology.Subpresheaf.to_sheafifyLift
File: Mathlib/CategoryTheory/Sites/Subsheaf.lean

tactic: ext U s
state_before: C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
⊢ homOfLe ⋯ ≫ G.sheafifyLift f h = f
state_after: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
⊢ (homOfLe ⋯ ≫ G.sheafifyLift f h).app U s = f.app U s

tactic: apply (h _ ((Subpresheaf.homOfLe (G.le_sheafify J)).app U s).prop).isSeparatedFor.ext
state_before: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
⊢ (homOfLe ⋯ ≫ G.sheafifyLift f h).app U s = f.app U s
state_after: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
⊢ ∀ ⦃Y : C⦄ ⦃f_1 : Y ⟶ U.unop⦄,
    (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows f_1 →
      F'.map f_1.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map f_1.op (f.app U s)

tactic: intro V i hi
state_before: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
⊢ ∀ ⦃Y : C⦄ ⦃f_1 : Y ⟶ U.unop⦄,
    (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows f_1 →
      F'.map f_1.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map f_1.op (f.app U s)
state_after: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
V : C
i : V ⟶ U.unop
hi : (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows i
⊢ F'.map i.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map i.op (f.app U s)

tactic: have := elementwise_of% f.naturality
state_before: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
V : C
i : V ⟶ U.unop
hi : (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows i
⊢ F'.map i.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map i.op (f.app U s)
state_after: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
V : C
i : V ⟶ U.unop
hi : (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows i
this : ∀ ⦃X Y : Cᵒᵖ⦄ (f_1 : X ⟶ Y) (x : G.toPresheaf.obj X), f.app Y (G.toPresheaf.map f_1 x) = F'.map f_1 (f.app X x)
⊢ F'.map i.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map i.op (f.app U s)

tactic: exact (Presieve.IsSheafFor.valid_glue (h _ ((homOfLe (_ : G ≤ sheafify J G)).app U s).2)
  ((G.family_of_elements_compatible _).compPresheafMap _) _ hi).trans (this _ _)
state_before: case w.h.h
C : Type u
inst✝ : Category.{v, u} C
J : GrothendieckTopology C
F F' F'' : Cᵒᵖ ⥤ Type w
G G' : Subpresheaf F
f : G.toPresheaf ⟶ F'
h : Presieve.IsSheaf J F'
U : Cᵒᵖ
s : G.toPresheaf.obj U
V : C
i : V ⟶ U.unop
hi : (G.sieveOfSection ↑((homOfLe ⋯).app U s)).arrows i
this : ∀ ⦃X Y : Cᵒᵖ⦄ (f_1 : X ⟶ Y) (x : G.toPresheaf.obj X), f.app Y (G.toPresheaf.map f_1 x) = F'.map f_1 (f.app X x)
⊢ F'.map i.op ((homOfLe ⋯ ≫ G.sheafifyLift f h).app U s) = F'.map i.op (f.app U s)
state_after: no goals