-- Mathlib/CategoryTheory/Localization/Predicate.lean
lemma areEqualizedByLocalization_iff [L.IsLocalization W] :
    AreEqualizedByLocalization W f g ↔ L.map f = L.map g

Proof state:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ e.inv.app X ≫ (W.Q ⋙ (Localization.uniq W.Q L W).functor).map f ≫ e.hom.app Y =
    e.inv.app X ≫ (W.Q ⋙ (Localization.uniq W.Q L W).functor).map g ≫ e.hom.app Y

Tactic:
dsimp

Result:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ e.inv.app X ≫ (Localization.uniq W.Q L W).functor.map (W.Q.map f) ≫ e.hom.app Y =
    e.inv.app X ≫ (Localization.uniq W.Q L W).functor.map (W.Q.map g) ≫ e.hom.app Y

Proof state:
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ W.Q.map f = W.Q.map g ↔ L.map f = L.map g

Tactic:
constructor

Result:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ W.Q.map f = W.Q.map g → L.map f = L.map g

case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ L.map f = L.map g → W.Q.map f = W.Q.map g

Proof state:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
⊢ W.Q.map f = W.Q.map g

Tactic:
let e := Localization.compUniqFunctor L W.Q W

Result:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ W.Q.map f = W.Q.map g

Proof state:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ e.inv.app X ≫ (L ⋙ (Localization.uniq L W.Q W).functor).map f ≫ e.hom.app Y =
    e.inv.app X ≫ (L ⋙ (Localization.uniq L W.Q W).functor).map g ≫ e.hom.app Y

Tactic:
dsimp

Result:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ e.inv.app X ≫ (Localization.uniq L W.Q W).functor.map (L.map f) ≫ e.hom.app Y =
    e.inv.app X ≫ (Localization.uniq L W.Q W).functor.map (L.map g) ≫ e.hom.app Y

Proof state:
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ AreEqualizedByLocalization W f g ↔ L.map f = L.map g

Tactic:
dsimp [AreEqualizedByLocalization]

Result:
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ W.Q.map f = W.Q.map g ↔ L.map f = L.map g

Proof state:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ e.inv.app X ≫ (Localization.uniq L W.Q W).functor.map (L.map f) ≫ e.hom.app Y =
    e.inv.app X ≫ (Localization.uniq L W.Q W).functor.map (L.map g) ≫ e.hom.app Y

Tactic:
rw [h]

Result:
no goals

Proof state:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ L.map f = L.map g

Tactic:
rw [← NatIso.naturality_1 e f, ← NatIso.naturality_1 e g]

Result:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ e.inv.app X ≫ (W.Q ⋙ (Localization.uniq W.Q L W).functor).map f ≫ e.hom.app Y =
    e.inv.app X ≫ (W.Q ⋙ (Localization.uniq W.Q L W).functor).map g ≫ e.hom.app Y

Proof state:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
⊢ W.Q.map f = W.Q.map g → L.map f = L.map g

Tactic:
intro h

Result:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
⊢ L.map f = L.map g

Proof state:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ e.inv.app X ≫ (Localization.uniq W.Q L W).functor.map (W.Q.map f) ≫ e.hom.app Y =
    e.inv.app X ≫ (Localization.uniq W.Q L W).functor.map (W.Q.map g) ≫ e.hom.app Y

Tactic:
rw [h]

Result:
no goals

Proof state:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
⊢ L.map f = L.map g

Tactic:
let e := Localization.compUniqFunctor W.Q L W

Result:
case mp
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : W.Q.map f = W.Q.map g
e : W.Q ⋙ (Localization.uniq W.Q L W).functor ≅ L := Localization.compUniqFunctor W.Q L W
⊢ L.map f = L.map g

Proof state:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ W.Q.map f = W.Q.map g

Tactic:
rw [← NatIso.naturality_1 e f, ← NatIso.naturality_1 e g]

Result:
case mpr
C : Type u_1
D : Type u_2
inst✝² : Category.{u_4, u_1} C
inst✝¹ : Category.{u_5, u_2} D
L : C ⥤ D
W : MorphismProperty C
X Y : C
f g : X ⟶ Y
inst✝ : L.IsLocalization W
h : L.map f = L.map g
e : L ⋙ (Localization.uniq L W.Q W).functor ≅ W.Q := Localization.compUniqFunctor L W.Q W
⊢ e.inv.app X ≫ (L ⋙ (Localization.uniq L W.Q W).functor).map f ≫ e.hom.app Y =
    e.inv.app X ≫ (L ⋙ (Localization.uniq L W.Q W).functor).map g ≫ e.hom.app Y