Theorem: CategoryTheory.Abelian.has_injective_coseparator
File: Mathlib/CategoryTheory/Abelian/Generator.lean

Proof steps:
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
⊢ ∃ G, Injective G ∧ IsCoseparator G
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this : WellPowered C
⊢ ∃ G, Injective G ∧ IsCoseparator G
tactic: haveI : WellPowered C := wellPowered_of_isDetector G hG.isDetector
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this : WellPowered C
⊢ ∃ G, Injective G ∧ IsCoseparator G
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
⊢ ∃ G, Injective G ∧ IsCoseparator G
tactic: haveI : HasProductsOfShape (Subobject (op G)) C := hasProductsOfShape_of_small _ _
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
⊢ ∃ G, Injective G ∧ IsCoseparator G
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
⊢ ∃ G, Injective G ∧ IsCoseparator G
tactic: let T : C := Injective.under (piObj fun P : Subobject (op G) => unop P)
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
⊢ ∃ G, Injective G ∧ IsCoseparator G
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
⊢ f = 0
tactic: refine ⟨T, inferInstance, (Preadditive.isCoseparator_iff _).2 fun X Y f hf => ?_⟩
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
⊢ f = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
⊢ h ≫ f = 0
tactic: refine (Preadditive.isSeparator_iff _).1 hG _ fun h => ?_
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
⊢ h ≫ f = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
⊢ factorThruImage (h ≫ f) = 0
tactic: suffices hh : factorThruImage (h ≫ f) = 0 by
    rw [← Limits.image.fac (h ≫ f), hh, zero_comp]
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
⊢ factorThruImage (h ≫ f) = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
⊢ factorThruImage (h ≫ f) = 0
tactic: let R := Subobject.mk (factorThruImage (h ≫ f)).op
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
⊢ factorThruImage (h ≫ f) = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
⊢ factorThruImage (h ≫ f) = 0
tactic: let q₁ : image (h ≫ f) ⟶ unop R :=
    (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
⊢ factorThruImage (h ≫ f) = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
q₂ : unop (Subobject.underlying.obj R) ⟶ ∏ᶜ fun P => unop (Subobject.underlying.obj P) :=
  section_ (Pi.π (fun P => unop (Subobject.underlying.obj P)) R)
⊢ factorThruImage (h ≫ f) = 0
tactic: let q₂ : unop (R : Cᵒᵖ) ⟶ piObj fun P : Subobject (op G) => unop P :=
    section_ (Pi.π (fun P : Subobject (op G) => (unop P : C)) R)
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
q₂ : unop (Subobject.underlying.obj R) ⟶ ∏ᶜ fun P => unop (Subobject.underlying.obj P) :=
  section_ (Pi.π (fun P => unop (Subobject.underlying.obj P)) R)
⊢ factorThruImage (h ≫ f) = 0
state_after: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
q₂ : unop (Subobject.underlying.obj R) ⟶ ∏ᶜ fun P => unop (Subobject.underlying.obj P) :=
  section_ (Pi.π (fun P => unop (Subobject.underlying.obj P)) R)
q : image (h ≫ f) ⟶ T := q₁ ≫ q₂ ≫ Injective.ι (∏ᶜ fun P => unop (Subobject.underlying.obj P))
⊢ factorThruImage (h ≫ f) = 0
tactic: let q : image (h ≫ f) ⟶ T := q₁ ≫ q₂ ≫ Injective.ι _
state_before: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasLimits C
inst✝ : EnoughInjectives C
G : C
hG : IsSeparator G
this✝ : WellPowered C
this : HasProductsOfShape (Subobject (op G)) C
T : C := Injective.under (∏ᶜ fun P => unop (Subobject.underlying.obj P))
X Y : C
f : X ⟶ Y
hf : ∀ (h : Y ⟶ T), f ≫ h = 0
h : G ⟶ X
R : Subobject (op G) := Subobject.mk (factorThruImage (h ≫ f)).op
q₁ : image (h ≫ f) ⟶ unop (Subobject.underlying.obj R) :=
  (Subobject.underlyingIso (factorThruImage (h ≫ f)).op).unop.hom
q₂ : unop (Subobject.underlying.obj R) ⟶ ∏ᶜ fun P => unop (Subobject.underlying.obj P) :=
  section_ (Pi.π (fun P => unop (Subobject.underlying.obj P)) R)
q : image (h ≫ f) ⟶ T := q₁ ≫ q₂ ≫ Injective.ι (∏ᶜ fun P => unop (Subobject.underlying.obj P))
⊢ factorThruImage (h ≫ f) = 0
state_after: no goals
tactic: exact zero_of_comp_mono q
    (by rw [← Injective.comp_factorThru q (Limits.image.ι (h ≫ f)), Limits.image.fac_assoc,
      Category.assoc, hf, comp_zero])