mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.CategoryTheory.Limits.Constructions.LimitsOfProductsAndEqualizers

Goal state before:
pp: C : Type u
inst✝⁸ : Category.{v, u} C
J : Type w
inst✝⁷ : SmallCategory J
D : Type u₂
inst✝⁶ : Category.{v₂, u₂} D
inst✝⁵ : HasColimitsOfShape (Discrete J) C
inst✝⁴ : HasColimitsOfShape (Discrete ((p : J × J) × (p.1 ⟶ p.2))) C
inst✝³ : HasCoequalizers C
G : C ⥤ D
inst✝² : PreservesColimitsOfShape WalkingParallelPair G
inst✝¹ : PreservesColimitsOfShape (Discrete J) G
inst✝ : PreservesColimitsOfShape (Discrete ((p : J × J) × (p.1 ⟶ p.2))) G
K : J ⥤ C
P : C := ∐ K.obj
Q : C := ∐ fun f ↦ K.obj f.fst.1
s : Q ⟶ P := Sigma.desc fun f ↦ K.map f.snd ≫ colimit.ι (Discrete.functor K.obj) { as := f.fst.2 }
t : Q ⟶ P := Sigma.desc fun f ↦ colimit.ι (Discrete.functor K.obj) { as := f.fst.1 }
I : C := coequalizer s t
i : P ⟶ I := coequalizer.π s t
⊢ G.map (s ≫ i) = G.map (t ≫ i)

Tactic:
apply congrArg G.map

Goal state after:
C : Type u
inst✝⁸ : Category.{v, u} C
J : Type w
inst✝⁷ : SmallCategory J
D : Type u₂
inst✝⁶ : Category.{v₂, u₂} D
inst✝⁵ : HasColimitsOfShape (Discrete J) C
inst✝⁴ : HasColimitsOfShape (Discrete ((p : J × J) × (p.1 ⟶ p.2))) C
inst✝³ : HasCoequalizers C
G : C ⥤ D
inst✝² : PreservesColimitsOfShape WalkingParallelPair G
inst✝¹ : PreservesColimitsOfShape (Discrete J) G
inst✝ : PreservesColimitsOfShape (Discrete ((p : J × J) × (p.1 ⟶ p.2))) G
K : J ⥤ C
P : C := ⋯
Q : C := ⋯
s : Q ⟶ P := ⋯
t : Q ⟶ P := ⋯
I : C := ⋯
i : P ⟶ I := ⋯
⊢ s ≫ i = t ≫ i
Module: Mathlib.CategoryTheory.Abelian.Basic

Goal state before:
pp: case h₀
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
inst✝ : HasPullbacks C
X Y Z : C
f : X ⟶ Z
g : Y ⟶ Z
s : Fork (biprod.desc f (-g)) 0
m : s.pt ⟶ (pullbackToBiproductFork f g).pt
h : m ≫ Fork.ι (pullbackToBiproductFork f g) = s.ι
⊢ m ≫ pullback.fst f g = pullback.lift (s.ι ≫ biprod.fst) (s.ι ≫ biprod.snd) ⋯ ≫ pullback.fst f g

Tactic:
simp [← h]

Goal state after:
Module: Mathlib.CategoryTheory.Abelian.Basic

Goal state before:
pp: case h₁
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
inst✝ : HasPullbacks C
X Y Z : C
f : X ⟶ Z
g : Y ⟶ Z
s : Fork (biprod.desc f (-g)) 0
m : s.pt ⟶ (pullbackToBiproductFork f g).pt
h : m ≫ Fork.ι (pullbackToBiproductFork f g) = s.ι
⊢ m ≫ pullback.snd f g = pullback.lift (s.ι ≫ biprod.fst) (s.ι ≫ biprod.snd) ⋯ ≫ pullback.snd f g

Tactic:
simp [← h]

Goal state after:
Module: Mathlib.CategoryTheory.Abelian.Basic

Goal state before:
pp: case h₀
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
inst✝ : HasPushouts C
W X Y Z : C
f : X ⟶ Y
g : X ⟶ Z
s : Cofork (biprod.lift f (-g)) 0
m : (biproductToPushoutCofork f g).pt ⟶ s.pt
h : Cofork.π (biproductToPushoutCofork f g) ≫ m = s.π
⊢ pushout.inl f g ≫ m = pushout.inl f g ≫ pushout.desc (biprod.inl ≫ s.π) (biprod.inr ≫ s.π) ⋯

Tactic:
simp [← h]

Goal state after:
Module: Mathlib.CategoryTheory.Abelian.Basic

Goal state before:
pp: case h₁
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : Abelian C
inst✝ : HasPushouts C
W X Y Z : C
f : X ⟶ Y
g : X ⟶ Z
s : Cofork (biprod.lift f (-g)) 0
m : (biproductToPushoutCofork f g).pt ⟶ s.pt
h : Cofork.π (biproductToPushoutCofork f g) ≫ m = s.π
⊢ pushout.inr f g ≫ m = pushout.inr f g ≫ pushout.desc (biprod.inl ≫ s.π) (biprod.inr ≫ s.π) ⋯

Tactic:
simp [← h]

Goal state after:
Module: Mathlib.Algebra.Category.Grp.EpiMono

Goal state before:
pp: A B : GrpCat
f : A ⟶ B
b : ↑B
hb : b ∉ (Hom.hom f).range
r : b • ↑(Hom.hom f).range = ↑(Hom.hom f).range
⊢ False

Tactic:
nth_rw 2 [show (f.hom.range : Set B) = (1 : B) • f.hom.range from (one_leftCoset _).symm] at r

Goal state after:
A B : GrpCat
f : A ⟶ B
b : ↑B
hb : b ∉ (Hom.hom f).range
r : b • ↑(Hom.hom f).range = 1 • ↑(Hom.hom f).range
⊢ False
Module: Mathlib.Algebra.Homology.ShortComplex.LeftHomology

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : HasZeroMorphisms C
S S₁ S₂ S₃ : ShortComplex C
e : S₁ ≅ S₂
h₁ : S₁.LeftHomologyData
h₂ : S₂.LeftHomologyData
⊢ cyclesMap' e.hom h₁ h₂ ≫ cyclesMap' e.inv h₂ h₁ = 𝟙 h₁.K

Tactic:
rw [← cyclesMap'_comp, e.hom_inv_id, cyclesMap'_id]

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.PreservesHomology

Goal state before:
pp: C : Type u_1
D : Type u_2
inst✝⁶ : Category.{v_1, u_1} C
inst✝⁵ : Category.{v_2, u_2} D
inst✝⁴ : HasZeroMorphisms C
inst✝³ : HasZeroMorphisms D
S S₁ S₂ : ShortComplex C
φ : S₁ ⟶ S₂
h₁ : S₁.LeftHomologyData
h₂ : S₂.LeftHomologyData
ψ : LeftHomologyMapData φ h₁ h₂
F : C ⥤ D
inst✝² : F.PreservesZeroMorphisms
inst✝¹ : h₁.IsPreservedBy F
inst✝ : h₂.IsPreservedBy F
⊢ F.map ψ.φK ≫ (h₂.map F).i = (h₁.map F).i ≫ (F.mapShortComplex.map φ).τ₂

Tactic:
by simpa only [F.map_comp] using! F.congr_map ψ.commi

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.PreservesHomology

Goal state before:
pp: C : Type u_1
D : Type u_2
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Category.{v_2, u_2} D
inst✝³ : HasZeroMorphisms C
inst✝² : HasZeroMorphisms D
S S₁ S₂ : ShortComplex C
h : S.RightHomologyData
F : C ⥤ D
inst✝¹ : F.PreservesZeroMorphisms
inst✝ : h.IsPreservedBy F
this : PreservesColimit (parallelPair S.f 0) F
⊢ (S.map F).RightHomologyData

Tactic:
have := IsPreservedBy.hg' h F

Goal state after:
C : Type u_1
D : Type u_2
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Category.{v_2, u_2} D
inst✝³ : HasZeroMorphisms C
inst✝² : HasZeroMorphisms D
S S₁ S₂ : ShortComplex C
h : S.RightHomologyData
F : C ⥤ D
inst✝¹ : F.PreservesZeroMorphisms
inst✝ : h.IsPreservedBy F
this✝ : PreservesColimit (parallelPair S.f 0) F
this : PreservesLimit (parallelPair h.g' 0) F
⊢ (S.map F).RightHomologyData
Module: Mathlib.Algebra.Homology.ShortComplex.Abelian

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
S : ShortComplex C
D : Type u'
inst✝¹ : Category.{v', u'} D
inst✝ : HasZeroMorphisms D
⊢ S.LeftHomologyData

Tactic:
let γ := kernel.ι S.g ≫ cokernel.π S.f
  let f' := kernel.lift S.g S.f S.zero
  have hf' : f' = kernel.lift γ f' (by simp [γ, f']) ≫ kernel.ι γ := by rw [kernel.lift_ι]
  have wπ : f' ≫ cokernel.π (kernel.ι γ) = 0 := by
    rw [hf']
    simp only [assoc, cokernel.condition, comp_zero]
  let e : Abelian.image S.f ≅ kernel γ :=
    IsLimit.conePointUniqueUpToIso S.abelianImageToKernelIsKernel (limit.isLimit _)
  have he : e.hom ≫ kernel.ι γ = S.abelianImageToKernel :=
    IsLimit.conePointUniqueUpToIso_hom_comp _ _ WalkingParallelPair.zero
  have fac : f' = Abelian.factorThruImage S.f ≫ e.hom ≫ kernel.ι γ := by
    rw [hf', he]
    simp only [γ, f', kernel.lift_ι, abelianImageToKernel, ← cancel_mono (kernel.ι S.g),
      assoc]
  have hπ : IsColimit (CokernelCofork.ofπ _ wπ) :=
    CokernelCofork.IsColimit.ofπ _ _
    (fun x hx => cokernel.desc _ x (by
      simpa only [← cancel_epi e.hom, ← cancel_epi (Abelian.factorThruImage S.f),
        comp_zero, fac, assoc] using hx))
    (fun x hx => cokernel.π_desc _ _ _)
    (fun x hx b hb => coequalizer.hom_ext (by simp only [hb, cokernel.π_desc]))
  exact
    { K := kernel S.g,
      H := Abelian.coimage (kernel.ι S.g ≫ cokernel.π S.f)
      i := kernel.ι _,
      π := cokernel.π _
      wi := kernel.condition _
      hi := kernelIsKernel _
      wπ := wπ
      hπ := hπ }

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Abelian

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
S : ShortComplex C
D : Type u'
inst✝¹ : Category.{v', u'} D
inst✝ : HasZeroMorphisms D
⊢ S.f ≫ Abelian.coimage.π S.g = 0

Tactic:
simp only [← cancel_mono (Abelian.factorThruCoimage S.g), assoc,
      cokernel.π_desc, zero, zero_comp]

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Abelian

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
S : ShortComplex C
D : Type u'
inst✝¹ : Category.{v', u'} D
inst✝ : HasZeroMorphisms D
γ : kernel S.g ⟶ cokernel S.f := kernel.ι S.g ≫ cokernel.π S.f
g' : cokernel S.f ⟶ S.X₃ := cokernel.desc S.f S.g ⋯
hg' : g' = cokernel.π γ ≫ cokernel.desc γ g' ⋯
wι : kernel.ι (cokernel.π γ) ≫ g' = 0
e : cokernel γ ≅ Abelian.coimage S.g :=
  (colimit.isColimit (parallelPair (kernel.ι S.g ≫ cokernel.π S.f) 0)).coconePointUniqueUpToIso
    S.cokernelToAbelianCoimageIsCokernel
he : cokernel.π γ ≫ e.hom = S.cokernelToAbelianCoimage
⊢ cokernel.π γ ≫ cokernel.desc γ g' ⋯ = cokernel.π γ ≫ e.hom ≫ Abelian.factorThruCoimage S.g

Tactic:
reassoc_of% he

Goal state after:
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
S : ShortComplex C
D : Type u'
inst✝¹ : Category.{v', u'} D
inst✝ : HasZeroMorphisms D
γ : kernel S.g ⟶ cokernel S.f := kernel.ι S.g ≫ cokernel.π S.f
g' : cokernel S.f ⟶ S.X₃ := cokernel.desc S.f S.g ⋯
hg' : g' = cokernel.π γ ≫ cokernel.desc γ g' ⋯
wι : kernel.ι (cokernel.π γ) ≫ g' = 0
e : cokernel γ ≅ Abelian.coimage S.g :=
  (colimit.isColimit (parallelPair (kernel.ι S.g ≫ cokernel.π S.f) 0)).coconePointUniqueUpToIso
    S.cokernelToAbelianCoimageIsCokernel
he : cokernel.π γ ≫ e.hom = S.cokernelToAbelianCoimage
⊢ cokernel.π γ ≫ cokernel.desc γ g' ⋯ = S.cokernelToAbelianCoimage ≫ Abelian.factorThruCoimage S.g
Module: Mathlib.CategoryTheory.Abelian.Opposite

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Abelian C
A B : Cᵒᵖ
g : A ⟶ B
⊢ (image.ι g.unop).op ≫ (imageUnopOp g).hom = factorThruImage g

Tactic:
simp only [imageUnopOp, Iso.trans, Iso.symm, Iso.op, cokernelOpOp_inv, cokernelEpiComp_hom,
    cokernelCompIsIso_hom, Abelian.coimageIsoImage'_hom, ← Category.assoc, ← op_comp]

Goal state after:
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Abelian C
A B : Cᵒᵖ
g : A ⟶ B
⊢ (((((kernel.lift (cokernel.π g.unop) (cokernel.π (cokernel.π g.unop).op).unop ⋯ ≫
                  (Abelian.imageIsoImage g.unop).hom) ≫
                image.ι g.unop).op ≫
            (cokernelIsoOfEq ⋯).hom) ≫
          cokernel.desc ((cokernelUnopOp g).hom ≫ kernel.ι g ≫ eqToHom ⋯) (cokernel.π (kernel.ι g ≫ eqToHom ⋯)) ⋯) ≫
        cokernel.desc (kernel.ι g ≫ eqToHom ⋯) (inv (eqToHom ⋯) ≫ cokernel.π (kernel.ι g)) ⋯) ≫
      cokernel.desc (kernel.ι g) (factorThruImage g) ⋯ =
    factorThruImage g
Module: Mathlib.CategoryTheory.Abelian.Opposite

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Abelian C
A B : Cᵒᵖ
g : A ⟶ B
⊢ (imageUnopOp g).inv ≫ (factorThruImage g.unop).op = image.ι g

Tactic:
rw [Iso.inv_comp_eq, imageUnopOp_hom_comp_image_ι]

Goal state after:
Module: Mathlib.CategoryTheory.Preadditive.Projective.Basic

Goal state before:
pp: C : Type u
inst✝⁴ : Category.{v, u} C
D : Type u_1
inst✝³ : Category.{v_1, u_1} D
F : C ⥤ D
inst✝² : F.Full
inst✝¹ : F.Faithful
inst✝ : F.PreservesEpimorphisms
P : C
hP : Projective (F.obj P)
E✝ X✝ : C
g : P ⟶ X✝
f : E✝ ⟶ X✝
x✝ : Epi f
h : F.obj P ⟶ F.obj E✝
fac : h ≫ F.map f = F.map g
⊢ F.map (F.preimage h ≫ f) = F.map g

Tactic:
by simp [fac]

Goal state after:
Module: Mathlib.CategoryTheory.Preadditive.Injective.Basic

Goal state before:
pp: C : Type u₁
inst✝⁴ : Category.{v₁, u₁} C
D : Type u_1
inst✝³ : Category.{v_1, u_1} D
F : C ⥤ D
inst✝² : F.Full
inst✝¹ : F.Faithful
inst✝ : F.PreservesMonomorphisms
I : C
hI : Injective (F.obj I)
X✝ Y✝ : C
g : X✝ ⟶ I
f : X✝ ⟶ Y✝
x✝ : Mono f
h : F.obj Y✝ ⟶ F.obj I
fac : F.map f ≫ h = F.map g
⊢ F.map (f ≫ F.preimage h) = F.map g

Tactic:
by simp [fac]

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : HasZeroMorphisms C
S : ShortComplex C
h : S.HomologyData
⊢ S.Exact ↔ IsZero h.left.H

Tactic:
have := HasHomology.mk' h
  exact LeftHomologyData.exact_iff h.left

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : HasZeroMorphisms C
S : ShortComplex C
h : S.Exact
X Y : C
a : X ⟶ S.X₂
ha : a ≫ S.g = 0
b : S.X₂ ⟶ Y
hb : S.f ≫ b = 0
this : S.HasHomology
eq : S.iCycles ≫ S.pOpcycles = 0
⊢ a ≫ b = 0

Tactic:
rw [← S.liftCycles_i a ha, ← S.p_descOpcycles b hb, assoc, reassoc_of% eq,
    zero_comp, comp_zero]

Goal state after:
Module: Mathlib.CategoryTheory.Adjunction.Reflective

Goal state before:
pp: C : Type u₁
D : Type u₂
inst✝³ : Category.{v₁, u₁} C
inst✝² : Category.{v₂, u₂} D
i : D ⥤ C
inst✝¹ : Reflective i
A : C
inst✝ : IsSplitMono ((reflectorAdjunction i).unit.app A)
η : 𝟭 C ⟶ reflector i ⋙ i := (reflectorAdjunction i).unit
this : IsIso (η.app (i.obj ((reflector i).obj A)))
⊢ Epi (η.app A)

Tactic:
refine @epi_of_epi _ _ _ _ _ (retraction (η.app A)) (η.app A) ?_

Goal state after:
C : Type u₁
D : Type u₂
inst✝³ : Category.{v₁, u₁} C
inst✝² : Category.{v₂, u₂} D
i : D ⥤ C
inst✝¹ : Reflective i
A : C
inst✝ : IsSplitMono ((reflectorAdjunction i).unit.app A)
η : 𝟭 C ⟶ reflector i ⋙ i := (reflectorAdjunction i).unit
this : IsIso (η.app (i.obj ((reflector i).obj A)))
⊢ Epi (retraction (η.app A) ≫ η.app A)
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : Preadditive C
S : ShortComplex C
inst✝¹ : S.HasHomology
inst✝ : HasCokernel S.f
⊢ S.Exact ↔ Mono (cokernel.desc S.f S.g ⋯)

Tactic:
rw [exact_iff_mono_fromOpcycles]
  refine (MorphismProperty.monomorphisms C).arrow_mk_iso_iff (Iso.symm ?_)
  exact Arrow.isoMk S.opcyclesIsoCokernel.symm (Iso.refl _) (by cat_disch)

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : Preadditive C
S₁ S₂ : ShortComplex C
φ : S₁ ⟶ S₂
inst✝² : S₁.HasHomology
inst✝¹ : S₂.HasHomology
inst✝ : QuasiIso φ
⊢ S₁.Exact ↔ S₂.Exact

Tactic:
simp only [exact_iff_isZero_homology]
  exact Iso.isZero_iff (asIso (homologyMap φ))

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S : ShortComplex C
hS : S.Exact
hf : S.f = 0
this✝¹ : S.HasHomology
this✝ : Epi S.toCycles
this : S.iCycles = 0
A : C
x₂ : A ⟶ S.X₂
hx₂ : x₂ ≫ S.g = 0
⊢ x₂ = 0

Tactic:
rw [← S.liftCycles_i x₂ hx₂, this, comp_zero]

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S : ShortComplex C
hS : S.Exact
⊢ Epi S.f ↔ S.g = 0

Tactic:
by
  constructor
  · intro
    rw [← cancel_epi S.f, zero, comp_zero]
  · exact hS.epi_f

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S : ShortComplex C
hS : S.Exact
⊢ IsZero S.X₂ ↔ S.f = 0 ∧ S.g = 0

Tactic:
constructor
  · intro h
    exact ⟨h.eq_of_tgt _ _, h.eq_of_src _ _⟩
  · rintro ⟨hf, hg⟩
    exact hS.isZero_X₂ hf hg

Goal state after:
Module: Mathlib.Algebra.Homology.ShortComplex.Exact

Goal state before:
pp: C : Type u_1
D : Type u_2
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : Category.{v_2, u_2} D
inst✝² : Preadditive C
inst✝¹ : Preadditive D
S : ShortComplex C
s : S.Splitting
F : C ⥤ D
inst✝ : F.Additive
⊢ F.map s.r ≫ (S.map F).f + (S.map F).g ≫ F.map s.s = 𝟙 (S.map F).X₂

Tactic:
by
    dsimp [ShortComplex.map]
    simp only [← F.map_id, ← s.id, Functor.map_comp, Functor.map_add]

Goal state after:
Module: Mathlib.CategoryTheory.Abelian.Exact

Goal state before:
pp: C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
inst✝ : Abelian C
S : ShortComplex C
⊢ S.Exact ↔ Epi (imageToKernel' S.f S.g ⋯)

Tactic:
S.exact_iff_epi_kernel_lift

Goal state after:
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
inst✝ : Abelian C
S : ShortComplex C
⊢ Epi (kernel.lift S.g S.f ⋯) ↔ Epi (imageToKernel' S.f S.g ⋯)
Module: Mathlib.Algebra.Homology.ShortComplex.ExactFunctor

Goal state before:
pp: C : Type u_1
D : Type u_2
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : Category.{v_2, u_2} D
inst✝² : Abelian C
inst✝¹ : Abelian D
F : C ⥤ D
inst✝ : F.Additive
hF : ∀ (S : ShortComplex C), S.ShortExact → (S.map F).Exact ∧ Epi (F.map S.g)
S : ShortComplex C
hS : S.Exact
hf : Epi S.g
this : F.PreservesEpimorphisms
T : ShortComplex C := { X₁ := Abelian.image S.f, X₂ := S.X₂, X₃ := S.X₃, f := Abelian.image.ι S.f, g := S.g, zero := ⋯ }
⊢ (S.map F).Exact

Tactic:
let φ : S.map F ⟶ T.map F :=
      { τ₁ := F.map <| Abelian.factorThruImage S.f
        τ₂ := 𝟙 _
        τ₃ := 𝟙 _
        comm₁₂ := show _ ≫ F.map (kernel.ι _) = F.map _ ≫ 𝟙 _ by
          rw [← F.map_comp, Abelian.image.fac, Category.comp_id] }

Goal state after:
C : Type u_1
D : Type u_2
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : Category.{v_2, u_2} D
inst✝² : Abelian C
inst✝¹ : Abelian D
F : C ⥤ D
inst✝ : F.Additive
hF : ∀ (S : ShortComplex C), S.ShortExact → (S.map F).Exact ∧ Epi (F.map S.g)
S : ShortComplex C
hS : S.Exact
hf : Epi S.g
this : F.PreservesEpimorphisms
T : ShortComplex C := { X₁ := Abelian.image S.f, X₂ := S.X₂, X₃ := S.X₃, f := Abelian.image.ι S.f, g := S.g, zero := ⋯ }
φ : S.map F ⟶ T.map F :=
  { τ₁ := F.map (Abelian.factorThruImage S.f), τ₂ := 𝟙 (S.map F).X₂, τ₃ := 𝟙 (S.map F).X₃, comm₁₂ := ⋯, comm₂₃ := ⋯ }
⊢ (S.map F).Exact
Module: Mathlib.CategoryTheory.Subobject.Lattice

Goal state before:
pp: case refine_4
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
inst✝ : HasPullbacks C
A : C
f g : Subobject A
x✝² : PullbackCone f.arrow g.arrow
x✝¹ : x✝².pt ⟶ underlying.obj (f ⊓ g)
h : x✝¹ ≫ (f ⊓ g).ofLE f ⋯ = x✝².fst
x✝ : x✝¹ ≫ (f ⊓ g).ofLE g ⋯ = x✝².snd
⊢ x✝¹ ≫ (f ⊓ g).arrow = (f ⊓ g).factorThru (x✝².fst ≫ f.arrow) ⋯ ≫ (f ⊓ g).arrow

Tactic:
simp [← h]

Goal state after:
Module: Mathlib.CategoryTheory.Functor.KanExtension.Basic

Goal state before:
pp: case mpr
C : Type u_1
H : Type u_3
D : Type u_4
inst✝² : Category.{v_1, u_1} C
inst✝¹ : Category.{v_3, u_3} H
inst✝ : Category.{v_4, u_4} D
F' F'' : D ⥤ H
e : F' ≅ F''
L : C ⥤ D
F : C ⥤ H
α : F ⟶ L ⋙ F'
α' : F ⟶ L ⋙ F''
comm : α ≫ L.whiskerLeft e.hom = α'
a✝ : F''.IsLeftKanExtension α'
⊢ F'.IsLeftKanExtension α

Tactic:
refine isLeftKanExtension_of_iso e.symm α' α ?_

Goal state after:
case mpr
C : Type u_1
H : Type u_3
D : Type u_4
inst✝² : Category.{v_1, u_1} C
inst✝¹ : Category.{v_3, u_3} H
inst✝ : Category.{v_4, u_4} D
F' F'' : D ⥤ H
e : F' ≅ F''
L : C ⥤ D
F : C ⥤ H
α : F ⟶ L ⋙ F'
α' : F ⟶ L ⋙ F''
comm : α ≫ L.whiskerLeft e.hom = α'
a✝ : F''.IsLeftKanExtension α'
⊢ α' ≫ L.whiskerLeft e.symm.hom = α
Module: Mathlib.CategoryTheory.Comma.Presheaf.Basic

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
A : Cᵒᵖ ⥤ Type v
F G : (CostructuredArrow yoneda A)ᵒᵖ ⥤ Type v
η : F ⟶ G
⊢ ∀ ⦃X Y : Cᵒᵖ⦄ (f : X ⟶ Y),
    (yonedaCollectionPresheaf A F).map f ≫ ↾YonedaCollection.map₁ η =
      ↾YonedaCollection.map₁ η ≫ (yonedaCollectionPresheaf A G).map f

Tactic:
by
    intros
    ext
    simp

Goal state after:
Module: Mathlib.CategoryTheory.Functor.KanExtension.Basic

Goal state before:
pp: C : Type u_1
C' : Type u_2
H : Type u_3
D : Type u_4
D' : Type u_5
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Category.{v_2, u_2} C'
inst✝³ : Category.{v_3, u_3} H
inst✝² : Category.{v_4, u_4} D
inst✝¹ : Category.{v_5, u_5} D'
F' : D ⥤ H
L : C ⥤ D
F : C ⥤ H
α : F ⟶ L ⋙ F'
inst✝ : F'.IsLeftKanExtension α
c : Cocone F
hc : IsColimit c
s : Cocone F'
⊢ ∀ (j : D), (F'.coconeOfIsLeftKanExtension α c).ι.app j ≫ hc.desc { pt := s.1, ι := α ≫ L.whiskerLeft s.ι } = s.ι.app j

Tactic:
have : F'.descOfIsLeftKanExtension α ((const D).obj c.pt) c.ι ≫
        (Functor.const _).map (hc.desc (Cocone.mk _ (α ≫ whiskerLeft L s.ι))) = s.ι :=
      F'.hom_ext_of_isLeftKanExtension α _ _ (by cat_disch)

Goal state after:
C : Type u_1
C' : Type u_2
H : Type u_3
D : Type u_4
D' : Type u_5
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Category.{v_2, u_2} C'
inst✝³ : Category.{v_3, u_3} H
inst✝² : Category.{v_4, u_4} D
inst✝¹ : Category.{v_5, u_5} D'
F' : D ⥤ H
L : C ⥤ D
F : C ⥤ H
α : F ⟶ L ⋙ F'
inst✝ : F'.IsLeftKanExtension α
c : Cocone F
hc : IsColimit c
s : Cocone F'
this :
  F'.descOfIsLeftKanExtension α ((const D).obj c.pt) c.ι ≫
      (const D).map (hc.desc { pt := s.1, ι := α ≫ L.whiskerLeft s.ι }) =
    s.ι
⊢ ∀ (j : D), (F'.coconeOfIsLeftKanExtension α c).ι.app j ≫ hc.desc { pt := s.1, ι := α ≫ L.whiskerLeft s.ι } = s.ι.app j
Module: Mathlib.CategoryTheory.Limits.Presheaf

Goal state before:
pp: C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
ℰ : Type u₂
inst✝ : Category.{v₂, u₂} ℰ
A : C ⥤ ℰ
P : Cᵒᵖ ⥤ Type (max w v₁)
s : Cocone (functorToRepresentables P)
X Y : Cᵒᵖ
f : X ⟶ Y
x : P.obj X
this :
  uliftYoneda.{w, v₁, u₁}.map f.unop ≫ s.ι.app (op (P.elementsMk X x)) =
    s.ι.app (op (P.elementsMk Y ((hom (P.map f)) x)))
⊢ (hom ((s.ι.app (op (P.elementsMk X x))).app Y))
      ((hom ((uliftYoneda.{w, v₁, u₁}.map f.unop).app (op (unop Y)))) { down := 𝟙 (unop Y) }) =
    (hom (s.pt.map f)) ((hom ((s.ι.app (op (P.elementsMk X x))).app (op (unop X)))) { down := 𝟙 (unop X) })

Tactic:
← NatTrans.naturality_apply

Goal state after:
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
ℰ : Type u₂
inst✝ : Category.{v₂, u₂} ℰ
A : C ⥤ ℰ
P : Cᵒᵖ ⥤ Type (max w v₁)
s : Cocone (functorToRepresentables P)
X Y : Cᵒᵖ
f : X ⟶ Y
x : P.obj X
this :
  uliftYoneda.{w, v₁, u₁}.map f.unop ≫ s.ι.app (op (P.elementsMk X x)) =
    s.ι.app (op (P.elementsMk Y ((hom (P.map f)) x)))
⊢ (hom ((s.ι.app (op (P.elementsMk X x))).app Y))
      ((hom ((uliftYoneda.{w, v₁, u₁}.map f.unop).app (op (unop Y)))) { down := 𝟙 (unop Y) }) =
    (hom ((s.ι.app (op (P.elementsMk X x))).app Y))
      ((hom ((uliftYoneda.{w, v₁, u₁}.obj (unop X)).map f)) { down := 𝟙 (unop X) })
Module: Mathlib.CategoryTheory.Limits.Constructions.WeaklyInitial

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasWideEqualizers C
T : C
hT : ∀ (X : C), Nonempty (T ⟶ X)
endos : Type v := T ⟶ T
i : wideEqualizer id ⟶ T := wideEqualizer.ι id
this✝¹ : Nonempty endos
X : C
a : wideEqualizer id ⟶ X
E : C := equalizer a (i ≫ Classical.choice ⋯)
e : E ⟶ wideEqualizer id := equalizer.ι a (i ≫ Classical.choice ⋯)
h : T ⟶ E := Classical.choice ⋯
this✝ : (i ≫ h) ≫ e = 𝟙 (wideEqualizer id)
this : IsSplitEpi e
⊢ a = default

Tactic:
← cancel_epi e

Goal state after:
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasWideEqualizers C
T : C
hT : ∀ (X : C), Nonempty (T ⟶ X)
endos : Type v := T ⟶ T
i : wideEqualizer id ⟶ T := wideEqualizer.ι id
this✝¹ : Nonempty endos
X : C
a : wideEqualizer id ⟶ X
E : C := equalizer a (i ≫ Classical.choice ⋯)
e : E ⟶ wideEqualizer id := equalizer.ι a (i ≫ Classical.choice ⋯)
h : T ⟶ E := Classical.choice ⋯
this✝ : (i ≫ h) ≫ e = 𝟙 (wideEqualizer id)
this : IsSplitEpi e
⊢ e ≫ a = e ≫ default
Module: Mathlib.CategoryTheory.Generator.Basic

Goal state before:
pp: C : Type u₁
inst✝ : Category.{v₁, u₁} C
P : ObjectProperty C
hP : ∀ (X : C), ∃ J x, P.colimitsOfShape J X
⊢ P.IsSeparating

Tactic:
intro X Y f g h
  obtain ⟨J, _, ⟨p⟩⟩ := hP X
  exact p.isColimit.hom_ext (fun j ↦ h _ (p.prop_diag_obj _) _)

Goal state after:
Module: Mathlib.Algebra.Ring.Periodic

Goal state before:
pp: α : Type u_1
β : Type u_2
f : α → β
c₁ c₂ : α
inst✝¹ : AddGroup α
inst✝ : InvolutiveNeg β
h1 : Antiperiodic f c₁
h2 : Antiperiodic f c₂
⊢ Periodic f (c₁ - c₂)

Tactic:
simpa only [sub_eq_add_neg] using h1.add h2.neg

Goal state after:
Module: Mathlib.Algebra.Module.Injective

Goal state before:
pp: R : Type u
inst✝⁷ : Ring R
Q : Type v
inst✝⁶ : AddCommGroup Q
inst✝⁵ : Module R Q
M : Type u_1
N : Type u_2
inst✝⁴ : AddCommGroup M
inst✝³ : AddCommGroup N
inst✝² : Module R M
inst✝¹ : Module R N
i : M →ₗ[R] N
f : M →ₗ[R] Q
inst✝ : Fact (Function.Injective ⇑i)
h : Baer R Q
y : N
⊢ y ∈ (extensionOfMax i f).domain

Tactic:
← extensionOfMax_is_max i f _ (extensionOfMax_le i f h),

Goal state after:
R : Type u
inst✝⁷ : Ring R
Q : Type v
inst✝⁶ : AddCommGroup Q
inst✝⁵ : Module R Q
M : Type u_1
N : Type u_2
inst✝⁴ : AddCommGroup M
inst✝³ : AddCommGroup N
inst✝² : Module R M
inst✝¹ : Module R N
i : M →ₗ[R] N
f : M →ₗ[R] Q
inst✝ : Fact (Function.Injective ⇑i)
h : Baer R Q
y : N
⊢ y ∈ (extensionOfMaxAdjoin i f h ?m.94).domain

R : Type u
inst✝⁷ : Ring R
Q : Type v
inst✝⁶ : AddCommGroup Q
inst✝⁵ : Module R Q
M : Type u_1
N : Type u_2
inst✝⁴ : AddCommGroup M
inst✝³ : AddCommGroup N
inst✝² : Module R M
inst✝¹ : Module R N
i : M →ₗ[R] N
f : M →ₗ[R] Q
inst✝ : Fact (Function.Injective ⇑i)
h : Baer R Q
y : N
⊢ N