-- Mathlib/CategoryTheory/SmallObject/IsCardinalForSmallObjectArgument.lean
lemma succStruct_prop_le_propArrow :
    (succStruct I κ).prop ≤ (propArrow.{w} I).functorCategory (Arrow C)

Proof state:
case mk
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
j : FunctorObjIndex I.homFamily (F.obj f).hom
⊢ ofHoms I.homFamily ((Discrete.natTrans fun X => functorObjLeftFamily I.homFamily (F.obj f).hom X.as).app { as := j })

Tactic:
constructor

Result:
no goals

Proof state:
case left
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ (coproducts.{w, v, u} I).pushouts (((succStruct I κ).toSucc F).app f).left

Tactic:
nth_rw 1 [← I.ofHoms_homFamily]

Result:
case left
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ (coproducts.{w, v, u} (ofHoms I.homFamily)).pushouts (((succStruct I κ).toSucc F).app f).left

Proof state:
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝¹ : LocallySmall.{w, v, u} C
this✝ : IsSmall.{w, v, u} I
this : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
⊢ (succStruct I κ).prop ≤ (propArrow I).functorCategory (Arrow C)

Tactic:
haveI := hasPushouts I κ

Result:
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
⊢ (succStruct I κ).prop ≤ (propArrow I).functorCategory (Arrow C)

Proof state:
case right
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ IsIso (((succStruct I κ).toSucc F).app f).right

Tactic:
dsimp [succStruct]

Result:
case right
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ IsIso (𝟙 (F.obj f).right)

Proof state:
case left
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ (coproducts.{w, v, u} (ofHoms I.homFamily)).pushouts (((succStruct I κ).toSucc F).app f).left

Tactic:
apply pushouts_mk _ (functorObj_isPushout I.homFamily (F.obj f).hom)

Result:
case left
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ coproducts.{w, v, u} (ofHoms I.homFamily) (functorObjLeft I.homFamily (F.obj f).hom)

Proof state:
case right
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ IsIso (𝟙 (F.obj f).right)

Tactic:
infer_instance

Result:
no goals

Proof state:
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
⊢ (succStruct I κ).prop ≤ (propArrow I).functorCategory (Arrow C)

Tactic:
intro _ _ _ ⟨F⟩ f

Result:
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ propArrow I (((succStruct I κ).toSucc F).app f)

Proof state:
case right
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ isomorphisms C (((succStruct I κ).toSucc F).app f).right

Tactic:
rw [MorphismProperty.isomorphisms.iff]

Result:
case right
C : Type u
inst✝³ : Category.{v, u} C
I : MorphismProperty C
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
inst✝¹ : OrderBot κ.ord.toType
inst✝ : I.IsCardinalForSmallObjectArgument κ
this✝² : LocallySmall.{w, v, u} C
this✝¹ : IsSmall.{w, v, u} I
this✝ : ∀ (X Y : C) (p : X ⟶ Y), HasColimitsOfShape (Discrete (FunctorObjIndex I.homFamily p)) C
this : HasPushouts C
X✝ Y✝ : Arrow C ⥤ Arrow C
f✝ : X✝ ⟶ Y✝
F : Arrow C ⥤ Arrow C
f : Arrow C
⊢ IsIso (((succStruct I κ).toSucc F).app f).right