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

Goal state before:
pp: C : Type u
inst✝⁵ : Category.{v, u} C
D : Type u'
inst✝⁴ : Category.{v', u'} D
G : C ⥤ D
inst✝³ : HasBinaryProducts C
inst✝² : HasPullbacks C
inst✝¹ : PreservesLimitsOfShape (Discrete WalkingPair) G
inst✝ : PreservesLimitsOfShape WalkingCospan G
K : WalkingParallelPair ⥤ C
c : Cone (K ⋙ G)
⊢ c.pt ⟶ (G.mapCone (equalizerCone K)).pt

Tactic:
refine pullback.lift ?_ ?_ ?_ ≫ (PreservesPullback.iso _ _ _ ).inv

Goal state after:
case refine_1
C : Type u
inst✝⁵ : Category.{v, u} C
D : Type u'
inst✝⁴ : Category.{v', u'} D
G : C ⥤ D
inst✝³ : HasBinaryProducts C
inst✝² : HasPullbacks C
inst✝¹ : PreservesLimitsOfShape (Discrete WalkingPair) G
inst✝ : PreservesLimitsOfShape WalkingCospan G
K : WalkingParallelPair ⥤ C
c : Cone (K ⋙ G)
⊢ c.pt ⟶ G.obj (K.obj WalkingParallelPair.zero)

case refine_2
C : Type u
inst✝⁵ : Category.{v, u} C
D : Type u'
inst✝⁴ : Category.{v', u'} D
G : C ⥤ D
inst✝³ : HasBinaryProducts C
inst✝² : HasPullbacks C
inst✝¹ : PreservesLimitsOfShape (Discrete WalkingPair) G
inst✝ : PreservesLimitsOfShape WalkingCospan G
K : WalkingParallelPair ⥤ C
c : Cone (K ⋙ G)
⊢ c.pt ⟶ G.obj (K.obj WalkingParallelPair.zero)

case refine_3
C : Type u
inst✝⁵ : Category.{v, u} C
D : Type u'
inst✝⁴ : Category.{v', u'} D
G : C ⥤ D
inst✝³ : HasBinaryProducts C
inst✝² : HasPullbacks C
inst✝¹ : PreservesLimitsOfShape (Discrete WalkingPair) G
inst✝ : PreservesLimitsOfShape WalkingCospan G
K : WalkingParallelPair ⥤ C
c : Cone (K ⋙ G)
⊢ ?refine_1 ≫ G.map (prod.lift (𝟙 (K.obj WalkingParallelPair.zero)) (K.map WalkingParallelPairHom.left)) =
    ?refine_2 ≫ G.map (prod.lift (𝟙 (K.obj WalkingParallelPair.zero)) (K.map WalkingParallelPairHom.right))
Module: Mathlib.LinearAlgebra.Contraction

Goal state before:
pp: R : Type u_7
M : Type u_8
N : Type u_9
ι : Type u_10
κ : Type u_11
inst✝⁸ : DecidableEq ι
inst✝⁷ : DecidableEq κ
inst✝⁶ : Fintype ι
inst✝⁵ : Fintype κ
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : AddCommMonoid N
inst✝¹ : Module R M
inst✝ : Module R N
b : Basis ι R M
c : Basis κ R N
f : Dual R (M ⊗[R] N)
⊢ (dualDistribInvOfBasis b c) f = ∑ i, ∑ j, f (b i ⊗ₜ[R] c j) • b.dualBasis i ⊗ₜ[R] c.dualBasis j

Tactic:
simp [dualDistribInvOfBasis]

Goal state after:
Module: Mathlib.LinearAlgebra.Dual.Lemmas

Goal state before:
pp: case e'_3
R : Type u_1
M : Type u_2
M' : Type u_3
inst✝⁴ : CommRing R
inst✝³ : AddCommGroup M
inst✝² : Module R M
inst✝¹ : AddCommGroup M'
inst✝ : Module R M'
f : M →ₗ[R] M'
hf : Function.Surjective ⇑f.range.subtype.dualMap
rr_surj : Function.Surjective ⇑f.rangeRestrict
this : f.rangeRestrict.dualMap.range = f.rangeRestrict.ker.dualAnnihilator
⊢ f.ker.dualAnnihilator = f.rangeRestrict.ker.dualAnnihilator

Tactic:
apply congr_arg

Goal state after:
case e'_3
R : Type u_1
M : Type u_2
M' : Type u_3
inst✝⁴ : CommRing R
inst✝³ : AddCommGroup M
inst✝² : Module R M
inst✝¹ : AddCommGroup M'
inst✝ : Module R M'
f : M →ₗ[R] M'
hf : Function.Surjective ⇑f.range.subtype.dualMap
rr_surj : Function.Surjective ⇑f.rangeRestrict
this : f.rangeRestrict.dualMap.range = f.rangeRestrict.ker.dualAnnihilator
⊢ f.ker = f.rangeRestrict.ker
Module: Mathlib.Algebra.Category.FGModuleCat.Limits

Goal state before:
pp: J✝ : Type
inst✝⁴ : SmallCategory J✝
inst✝³ : FinCategory J✝
k : Type u
inst✝² : Ring k
J : Type
inst✝¹ : Finite J
Z : J → ModuleCat k
inst✝ : ∀ (j : J), Module.Finite k ↑(Z j)
⊢ Module.Finite k ↑(ModuleCat.of k ((j : J) → ↑(Z j)))

Tactic:
unfold ModuleCat.of; infer_instance

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

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : NonPreadditiveAbelian C
A : C
hlp : prod.lift (𝟙 A) 0 ≫ prod.snd = 0
hp1 : IsLimit (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) :=
  Fork.IsLimit.mk (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) (fun s ↦ s.ι ≫ prod.fst) ⋯ ⋯
hp2 : IsColimit (CokernelCofork.ofπ prod.snd hlp) := epiIsCokernelOfKernel (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) hp1
Z : C
z : cokernel (diag A) ⟶ Z
hz : r A ≫ z = 0
h : prod.lift (𝟙 A) 0 ≫ cokernel.π (diag A) ≫ z = 0
t : (CokernelCofork.ofπ prod.snd hlp).pt ⟶ Z
ht : prod.snd ≫ t = cokernel.π (diag A) ≫ z
⊢ t = 0

Tactic:
rw [← Category.id_comp t]

Goal state after:
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : NonPreadditiveAbelian C
A : C
hlp : prod.lift (𝟙 A) 0 ≫ prod.snd = 0
hp1 : IsLimit (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) :=
  Fork.IsLimit.mk (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) (fun s ↦ s.ι ≫ prod.fst) ⋯ ⋯
hp2 : IsColimit (CokernelCofork.ofπ prod.snd hlp) := epiIsCokernelOfKernel (KernelFork.ofι (prod.lift (𝟙 A) 0) hlp) hp1
Z : C
z : cokernel (diag A) ⟶ Z
hz : r A ≫ z = 0
h : prod.lift (𝟙 A) 0 ≫ cokernel.π (diag A) ≫ z = 0
t : (CokernelCofork.ofπ prod.snd hlp).pt ⟶ Z
ht : prod.snd ≫ t = cokernel.π (diag A) ≫ z
⊢ 𝟙 (CokernelCofork.ofπ prod.snd hlp).pt ≫ t = 0
Module: Mathlib.CategoryTheory.Abelian.Basic

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : Abelian C
inst✝¹ : HasPushouts C
W X Y Z : C
f : X ⟶ Y
g : X ⟶ Z
inst✝ : Mono f
R : C
e : R ⟶ Z
h : e ≫ pushout.inr f g = 0
⊢ e = 0

Tactic:
by
    let u := biprod.lift (0 : R ⟶ Y) e
    have hu : u ≫ BiproductToPushoutIsCokernel.biproductToPushout f g = 0 := by simpa [u]
    have :=
      monoIsKernelOfCokernel _
        (BiproductToPushoutIsCokernel.isColimitBiproductToPushout f g)
    obtain ⟨d, hd⟩ := KernelFork.IsLimit.lift' this u hu
    dsimp at d
    dsimp [u] at hd
    have : d ≫ f = 0 := calc
      d ≫ f = d ≫ biprod.lift f (-g) ≫ biprod.fst := by rw [biprod.lift_fst]
      _ = u ≫ biprod.fst := by rw [← Category.assoc, hd]
      _ = 0 := biprod.lift_fst _ _
    have : d = 0 := (cancel_mono f).1 (by simpa)
    calc
      e = biprod.lift (0 : R ⟶ Y) e ≫ biprod.snd := by rw [biprod.lift_snd]
      _ = (d ≫ biprod.lift f (-g)) ≫ biprod.snd := by rw [← hd]
      _ = (0 ≫ biprod.lift f (-g)) ≫ biprod.snd := by rw [this]
      _ = 0 ≫ biprod.lift f (-g) ≫ biprod.snd := by rw [Category.assoc]
      _ = 0 := zero_comp

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

Goal state before:
pp: C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : HasZeroMorphisms C
S S₁ S₂ S₃ : ShortComplex C
e : S₁ ≅ S₂
inst✝¹ : S₁.HasLeftHomology
inst✝ : S₂.HasLeftHomology
⊢ leftHomologyMap e.hom ≫ leftHomologyMap e.inv = 𝟙 S₁.leftHomology

Tactic:
← leftHomologyMap_comp,

Goal state after:
C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : HasZeroMorphisms C
S S₁ S₂ S₃ : ShortComplex C
e : S₁ ≅ S₂
inst✝¹ : S₁.HasLeftHomology
inst✝ : S₂.HasLeftHomology
⊢ leftHomologyMap (e.hom ≫ e.inv) = 𝟙 S₁.leftHomology
Module: Mathlib.Algebra.Homology.ShortComplex.LeftHomology

Goal state before:
pp: C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : HasZeroMorphisms C
S S₁ S₂ S₃ : ShortComplex C
e : S₁ ≅ S₂
inst✝¹ : S₁.HasLeftHomology
inst✝ : S₂.HasLeftHomology
⊢ leftHomologyMap e.inv ≫ leftHomologyMap e.hom = 𝟙 S₂.leftHomology

Tactic:
← leftHomologyMap_comp,

Goal state after:
C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : HasZeroMorphisms C
S S₁ S₂ S₃ : ShortComplex C
e : S₁ ≅ S₂
inst✝¹ : S₁.HasLeftHomology
inst✝ : S₂.HasLeftHomology
⊢ leftHomologyMap (e.inv ≫ e.hom) = 𝟙 S₂.leftHomology
Module: Mathlib.Algebra.Homology.ShortComplex.LeftHomology

Goal state before:
pp: C : Type u_1
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : HasZeroMorphisms C
S₁ S₂ : ShortComplex C
φ : S₁ ⟶ S₂
h : S₁.LeftHomologyData
inst✝² : Epi φ.τ₁
inst✝¹ : IsIso φ.τ₂
inst✝ : Mono φ.τ₃
⊢ φ.τ₁ ≫ (ofEpiOfIsIsoOfMono φ h).f' = h.f'

Tactic:
rw [← cancel_mono (ofEpiOfIsIsoOfMono φ h).i, assoc, f'_i,
    ofEpiOfIsIsoOfMono_i, f'_i_assoc, φ.comm₁₂]

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

Goal state before:
pp: case refine_3
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : HasZeroMorphisms C
S₁ S₂ : ShortComplex C
φ : S₁ ⟶ S₂
h₂✝ : IsIso φ.τ₂
h₃ : Mono φ.τ₃
h₁ : S₁.LeftHomologyData
h₂ : S₂.LeftHomologyData
⊢ h₁.liftK (h₂.i ≫ inv φ.τ₂) ⋯ ≫ cyclesMap' φ h₁ h₂ = 𝟙 h₂.K

Tactic:
· simp only [← cancel_mono h₂.i, assoc, cyclesMap'_i, h₁.liftK_i_assoc,
      IsIso.inv_hom_id, comp_id, id_comp]

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

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasZeroMorphisms C
S₁ S₂ : ShortComplex C
φ : S₁ ⟶ S₂
inst✝¹ : S₁.HasHomology
inst✝ : S₂.HasHomology
h : Epi (cyclesMap φ)
⊢ Epi (homologyMap φ)

Tactic:
by
  have : Epi (S₁.homologyπ ≫ homologyMap φ) := by
    rw [homologyπ_naturality φ]
    apply epi_comp
  exact epi_of_epi S₁.homologyπ (homologyMap φ)

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

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : Abelian C
S : ShortComplex C
cc : CokernelCofork S.f
hcc : IsColimit cc
this : Epi (Cofork.π cc)
⊢ hcc.desc (CokernelCofork.ofπ S.g ⋯) = (S.isoOpcyclesOfIsColimit hcc).hom ≫ S.fromOpcycles

Tactic:
simp [← cancel_epi cc.π]

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

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁ S₂ S₃ : ShortComplex C
φ₁ φ₂ φ₃ φ₄ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ φ₁.τ₃ = h.h₂ ≫ S₂.g + h.h₃ + φ₂.τ₃

Tactic:
h.comm₃

Goal state after:
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁ S₂ S₃ : ShortComplex C
φ₁ φ₂ φ₃ φ₄ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ h.h₃ + h.h₂ ≫ S₂.g + φ₂.τ₃ = h.h₂ ≫ S₂.g + h.h₃ + φ₂.τ₃
Module: Mathlib.Algebra.Homology.ShortComplex.Preadditive

Goal state before:
pp: C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁✝ S₂✝ S₃ : ShortComplex C
φ₁✝ φ₂✝ φ₃ φ₄ : S₁✝ ⟶ S₂✝
S₁ S₂ : ShortComplex Cᵒᵖ
φ₁ φ₂ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ φ₁.τ₃ = h.h₂ ≫ S₂.g + h.h₃ + φ₂.τ₃

Tactic:
h.comm₃

Goal state after:
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁✝ S₂✝ S₃ : ShortComplex C
φ₁✝ φ₂✝ φ₃ φ₄ : S₁✝ ⟶ S₂✝
S₁ S₂ : ShortComplex Cᵒᵖ
φ₁ φ₂ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ h.h₃ + h.h₂ ≫ S₂.g + φ₂.τ₃ = h.h₂ ≫ S₂.g + h.h₃ + φ₂.τ₃
Module: Mathlib.Algebra.Homology.ShortComplex.Preadditive

Goal state before:
pp: case h₃
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁ S₂ : ShortComplex C
φ₁ φ₂ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ φ₁.τ₃ = φ₂.τ₃ + (h.h₂ ≫ S₂.g + h.h₃)

Tactic:
h.comm₃

Goal state after:
case h₃
C : Type u_1
inst✝¹ : Category.{v_1, u_1} C
inst✝ : Preadditive C
S₁ S₂ : ShortComplex C
φ₁ φ₂ : S₁ ⟶ S₂
h : Homotopy φ₁ φ₂
⊢ h.h₃ + h.h₂ ≫ S₂.g + φ₂.τ₃ = φ₂.τ₃ + (h.h₂ ≫ S₂.g + h.h₃)
Module: Mathlib.Algebra.Homology.ShortComplex.Ab

Goal state before:
pp: S : ShortComplex Ab
⊢ S.Exact ↔ Function.Surjective ⇑S.abToCycles

Tactic:
S.abLeftHomologyData.exact_iff_epi_f',

Goal state after:
S : ShortComplex Ab
⊢ Epi S.abLeftHomologyData.f' ↔ Function.Surjective ⇑S.abToCycles
Module: Mathlib.CategoryTheory.Adjunction.Reflective

Goal state before:
pp: C : Type u₁
D : Type u₂
inst✝² : Category.{v₁, u₁} C
inst✝¹ : Category.{v₂, u₂} D
j : C ⥤ D
inst✝ : Coreflective j
X : D
⊢ (coreflectorAdjunction j).counit.app (j.obj ((coreflector j).obj X)) =
    j.map ((coreflector j).map ((coreflectorAdjunction j).counit.app X))

Tactic:
by
  rw [← cancel_epi (j.map ((coreflectorAdjunction j).unit.app ((coreflector j).obj X))),
    ← j.map_comp]
  simp

Goal state after:
Module: Mathlib.CategoryTheory.Subobject.FactorThru

Goal state before:
pp: case mp
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
X✝ Y✝ Z : C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
X Y : C
P✝ : Subobject Y
f : X ⟶ Y
P Q : MonoOver Y
h : P ≅ Q
⊢ P.Factors f → Q.Factors f

Tactic:
rintro ⟨i, w⟩

Goal state after:
case mp
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
X✝ Y✝ Z : C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
X Y : C
P✝ : Subobject Y
f : X ⟶ Y
P Q : MonoOver Y
h : P ≅ Q
i : X ⟶ P.obj.left
w : i ≫ P.arrow = f
⊢ Q.Factors f
Module: Mathlib.CategoryTheory.Subobject.FactorThru

Goal state before:
pp: case mpr
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
X✝ Y✝ Z : C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
X Y : C
P✝ : Subobject Y
f : X ⟶ Y
P Q : MonoOver Y
h : P ≅ Q
⊢ Q.Factors f → P.Factors f

Tactic:
rintro ⟨i, w⟩

Goal state after:
case mpr
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
X✝ Y✝ Z : C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
X Y : C
P✝ : Subobject Y
f : X ⟶ Y
P Q : MonoOver Y
h : P ≅ Q
i : X ⟶ Q.obj.left
w : i ≫ Q.arrow = f
⊢ P.Factors f
Module: Mathlib.CategoryTheory.Subobject.Basic

Goal state before:
pp: case inr
C : Type u₁
inst✝² : Category.{v₁, u₁} C
X A₁ A₂ : C
i₁ : A₁ ⟶ X
i₂ : A₂ ⟶ X
inst✝¹ : Mono i₁
inst✝ : Mono i₂
f : A₁ ⟶ A₂
fac : f ≫ i₂ = i₁
hf : ¬IsIso f
h : mk i₁ = mk i₂
⊢ mk i₁ < mk i₂

Tactic:
· exfalso
    apply hf
    convert! (isoOfMkEqMk i₁ i₂ h).isIso_hom
    rw [← cancel_mono i₂, isoOfMkEqMk_hom, ofMkLEMk_comp, fac]

Goal state after:
Module: Mathlib.CategoryTheory.Subobject.MonoOver

Goal state before:
pp: C : Type u₁
inst✝² : Category.{v₁, u₁} C
X Y Z : C
D : Type u₂
inst✝¹ : Category.{v₂, u₂} D
f : X ⟶ Y
inst✝ : Mono f
g h : MonoOver X
e : (map f).obj g ⟶ (map f).obj h
⊢ ∃ a, (map f).map a = e

Tactic:
by
    refine ⟨homMk e.hom.left ?_, rfl⟩
    · rw [← cancel_mono f, assoc]
      apply w e

Goal state after:
Module: Mathlib.CategoryTheory.Subobject.Limits

Goal state before:
pp: C : Type u
inst✝³ : Category.{v, u} C
X Y : C
inst✝² : HasZeroMorphisms C
f : X ⟶ Y
inst✝¹ : HasKernel f
X' Y' : C
f' : X' ⟶ Y'
inst✝ : HasKernel f'
sq : Arrow.mk f ⟶ Arrow.mk f'
⊢ (kernelSubobjectIso f).hom ≫ kernel.map f f' sq.left sq.right ⋯ = kernelSubobjectMap sq ≫ (kernelSubobjectIso f').hom

Tactic:
simp [← Iso.comp_inv_eq, kernel_map_comp_kernelSubobjectIso_inv]

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

Goal state before:
pp: C : Type u_1
D : Type u_2
H : Type u_4
inst✝³ : Category.{v_1, u_1} C
inst✝² : Category.{v_2, u_2} D
inst✝¹ : Category.{v_4, u_4} H
L : C ⥤ D
F : C ⥤ H
inst✝ : L.HasPointwiseRightKanExtension F
G : D ⥤ H
α : L ⋙ G ⟶ F
Y : D
⊢ ((L.pointwiseRightKanExtension F).liftOfIsRightKanExtension (L.pointwiseRightKanExtensionCounit F) G α).app Y =
    limit.lift (StructuredArrow.proj Y L ⋙ F) (L.structuredArrowMapCone F G α Y)

Tactic:
let β : G ⟶ L.pointwiseRightKanExtension F :=
    { app := fun Y ↦ limit.lift _ (structuredArrowMapCone L F G α Y) }
  have h : (pointwiseRightKanExtension L F).liftOfIsRightKanExtension
      (pointwiseRightKanExtensionCounit L F) G α = β := by
    apply hom_ext_of_isRightKanExtension (α := pointwiseRightKanExtensionCounit L F)
    aesop
  exact NatTrans.congr_app h Y

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
inst✝⁴ : Category.{v_1, u_1} C
inst✝³ : Category.{v_2, u_2} C'
inst✝² : Category.{v_3, u_3} H
inst✝¹ : Category.{v_4, u_4} D
L : C ⥤ D
F : C ⥤ H
F' : D ⥤ H
G : C' ⥤ C
inst✝ : G.IsEquivalence
α : L ⋙ F' ⟶ F
⊢ F'.IsRightKanExtension α ↔ F'.IsRightKanExtension ((G.associator L F').hom ≫ G.whiskerLeft α)

Tactic:
let eq : (RightExtension.mk _ α).IsUniversal ≃ (RightExtension.mk _
      ((associator _ _ _).hom ≫ whiskerLeft G α)).IsUniversal :=
    (RightExtension.isUniversalPrecompEquiv L F G _).trans
    (IsTerminal.equivOfIso (CostructuredArrow.isoMk (Iso.refl _)))
  constructor
  · exact fun _ => ⟨⟨eq (isUniversalOfIsRightKanExtension _ _)⟩⟩
  · exact fun _ => ⟨⟨eq.symm (isUniversalOfIsRightKanExtension _ _)⟩⟩

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

Goal state before:
pp: case refine_2
C : Type u_1
H : Type u_3
D : Type u_4
D' : Type u_5
inst✝⁴ : Category.{v_1, u_1} 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'
L : C ⥤ D
L' : D ⥤ D'
F₀ : C ⥤ H
F₁ : D ⥤ H
α : F₀ ⟶ L ⋙ F₁
inst✝ : F₁.IsLeftKanExtension α
F₂ : D' ⥤ H
L'' : C ⥤ D'
e : L ⋙ L' ≅ L''
β : F₁ ⟶ L' ⋙ F₂
γ : F₀ ⟶ L'' ⋙ F₂
hγ : α ≫ L.whiskerLeft β ≫ (L.associator L' F₂).inv ≫ whiskerRight e.hom F₂ = γ
Ψ : (L ⋙ L').LeftExtension F₀ ≌ L''.LeftExtension F₀ := leftExtensionEquivalenceOfIso₁ e F₀
hα : StructuredArrow.IsUniversal (LeftExtension.mk F₁ α)
x✝ : F₂.IsLeftKanExtension γ
h : StructuredArrow.IsUniversal (LeftExtension.mk F₂ γ)
⊢ StructuredArrow.IsUniversal (LeftExtension.mk F₂ β)

Tactic:
apply LeftExtension.isUniversalOfPrecomp₂ α hα

Goal state after:
case refine_2
C : Type u_1
H : Type u_3
D : Type u_4
D' : Type u_5
inst✝⁴ : Category.{v_1, u_1} 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'
L : C ⥤ D
L' : D ⥤ D'
F₀ : C ⥤ H
F₁ : D ⥤ H
α : F₀ ⟶ L ⋙ F₁
inst✝ : F₁.IsLeftKanExtension α
F₂ : D' ⥤ H
L'' : C ⥤ D'
e : L ⋙ L' ≅ L''
β : F₁ ⟶ L' ⋙ F₂
γ : F₀ ⟶ L'' ⋙ F₂
hγ : α ≫ L.whiskerLeft β ≫ (L.associator L' F₂).inv ≫ whiskerRight e.hom F₂ = γ
Ψ : (L ⋙ L').LeftExtension F₀ ≌ L''.LeftExtension F₀ := ⋯
hα : StructuredArrow.IsUniversal (LeftExtension.mk F₁ α)
x✝ : F₂.IsLeftKanExtension γ
h : StructuredArrow.IsUniversal (LeftExtension.mk F₂ γ)
⊢ StructuredArrow.IsUniversal ((LeftExtension.precomp₂ L' α).obj (LeftExtension.mk F₂ β))
Module: Mathlib.CategoryTheory.Abelian.GrothendieckAxioms.Basic

Goal state before:
pp: C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : Abelian C
J : Type u'
inst✝² : Category.{v', u'} J
inst✝¹ : HasColimitsOfShape J C
inst✝ : colim.PreservesMonomorphisms
⊢ PreservesFiniteLimits colim

Tactic:
apply +allowSynthFailures preservesFiniteLimits_of_preservesHomology

Goal state after:
case inst
C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : Abelian C
J : Type u'
inst✝² : Category.{v', u'} J
inst✝¹ : HasColimitsOfShape J C
inst✝ : colim.PreservesMonomorphisms
⊢ colim.PreservesHomology

case inst
C : Type u
inst✝⁴ : Category.{v, u} C
inst✝³ : Abelian C
J : Type u'
inst✝² : Category.{v', u'} J
inst✝¹ : HasColimitsOfShape J C
inst✝ : colim.PreservesMonomorphisms
⊢ colim.Additive
Module: Mathlib.CategoryTheory.Limits.Shapes.WideEqualizers

Goal state before:
pp: case zero
J : Type w
C : Type u
inst✝¹ : Category.{v, u} C
X Y : C
f : J → (X ⟶ Y)
inst✝ : Nonempty J
s t : Cotrident f
k : s.pt ⟶ t.pt
w : s.π ≫ k = t.π
⊢ s.ι.app zero ≫ k = t.ι.app zero

Tactic:
simpa using f (Classical.arbitrary J) ≫= w

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

Goal state before:
pp: X'✝ X✝ : Type u
Y✝ : AddCommGrpCat
f✝ : X'✝ ⟶ X✝
g✝ : X✝ ⟶ (forget AddCommGrpCat).obj Y✝
x✝ : ↑(free.obj X'✝)
⊢ (FreeAbelianGroup.lift ⇑(ConcreteCategory.hom (f✝ ≫ g✝))) x✝ =
    (FreeAbelianGroup.lift ⇑(ConcreteCategory.hom g✝)) ((FreeAbelianGroup.map ⇑(ConcreteCategory.hom f✝)) x✝)

Tactic:
← FreeAbelianGroup.lift_comp

Goal state after:
X'✝ X✝ : Type u
Y✝ : AddCommGrpCat
f✝ : X'✝ ⟶ X✝
g✝ : X✝ ⟶ (forget AddCommGrpCat).obj Y✝
x✝ : ↑(free.obj X'✝)
⊢ (FreeAbelianGroup.lift ⇑(ConcreteCategory.hom (f✝ ≫ g✝))) x✝ =
    (FreeAbelianGroup.lift (⇑(ConcreteCategory.hom g✝) ∘ ⇑(ConcreteCategory.hom f✝))) x✝
Module: Mathlib.Algebra.Category.Grp.Adjunctions

Goal state before:
pp: ⊢ ∀ (X : GrpCat),
    CommGrpCat.ofHom (Abelianization.lift (Abelianization.of.comp (Hom.hom (𝟙 X)))) =
      𝟙 (CommGrpCat.of (Abelianization ↑X))

Tactic:
by
    intros
    ext : 1
    apply (Equiv.eq_symm_apply Abelianization.lift).mp
    rfl

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

Goal state before:
pp: ⊢ ∀ {X Y Z : GrpCat} (f : X ⟶ Y) (g : Y ⟶ Z),
    CommGrpCat.ofHom (Abelianization.lift (Abelianization.of.comp (Hom.hom (f ≫ g)))) =
      CommGrpCat.ofHom (Abelianization.lift (Abelianization.of.comp (Hom.hom f))) ≫
        CommGrpCat.ofHom (Abelianization.lift (Abelianization.of.comp (Hom.hom g)))

Tactic:
by
    intros
    ext : 1
    apply (Equiv.eq_symm_apply Abelianization.lift).mp
    rfl

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

Goal state before:
pp: A : Type u
inst✝¹ : AddCommGroup A
inst✝ : DivisibleBy A ℤ
I : Ideal ℤ
g : ↥I →ₗ[ℤ] A
⊢ ∃ g', ∀ (x : ℤ) (mem : x ∈ I), g' x = g ⟨x, mem⟩

Tactic:
rcases IsPrincipalIdealRing.principal I with ⟨m, rfl⟩

Goal state after:
A : Type u
inst✝¹ : AddCommGroup A
inst✝ : DivisibleBy A ℤ
m : ℤ
g : ↥(ℤ ∙ m) →ₗ[ℤ] A
⊢ ∃ g', ∀ (x : ℤ) (mem : x ∈ ℤ ∙ m), g' x = g ⟨x, mem⟩
Module: Mathlib.Algebra.Ring.Periodic

Goal state before:
pp: α : Type u_1
β : Type u_2
f : α → β
c : α
inst✝ : AddCommSemigroup α
h : Periodic f c
a x : α
⊢ (fun x ↦ f (x + a)) (x + c) = (fun x ↦ f (x + a)) x

Tactic:
simpa only [add_right_comm] using h (x + a)

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

Goal state before:
pp: α : Type u_1
β : Type u_2
f : α → β
c : α
inst✝¹ : NonAssocSemiring α
inst✝ : NegZeroClass β
h : Antiperiodic f c
hi : f 0 = 0
⊢ f (0 * c) = 0

Tactic:
zero_mul

Goal state after:
α : Type u_1
β : Type u_2
f : α → β
c : α
inst✝¹ : NonAssocSemiring α
inst✝ : NegZeroClass β
h : Antiperiodic f c
hi : f 0 = 0
⊢ f 0 = 0
Module: Mathlib.Algebra.Ring.Periodic

Goal state before:
pp: α : Type u_1
β : Type u_2
f : α → β
c : α
inst✝¹ : AddCommSemigroup α
inst✝ : Neg β
h : Antiperiodic f c
a x : α
⊢ (fun x ↦ f (x + a)) (x + c) = -(fun x ↦ f (x + a)) x

Tactic:
simpa only [add_right_comm] using h (x + a)

Goal state after:
Module: Mathlib.Data.Nat.Count

Goal state before:
pp: p : ℕ → Prop
inst✝ : DecidablePred p
⊢ count p 1 = if p 0 then 1 else 0

Tactic:
simp [count_succ]

Goal state after:
Module: Mathlib.Data.Nat.Totient

Goal state before:
pp: n : ℕ
hn : n > 0
⊢ n = ∑ d ∈ n.divisors, #({k ∈ range n | n.gcd k = d})

Tactic:
← card_range n

Goal state after:
n : ℕ
hn : n > 0
⊢ #(range n) = ∑ d ∈ n.divisors, #({k ∈ range n | n.gcd k = d})
Module: Mathlib.Data.Set.Constructions

Goal state before:
pp: α : Type u_1
S : Set (Set α)
A : Set α
cond : FiniteInter S
P T1 : Set α
a✝¹ : finiteInterClosure (insert A S) T1
h : T1 ∈ S
R : Set α
hR : R ∈ S
a✝ : finiteInterClosure (insert A S) (A ∩ R)
⊢ T1 ∩ (A ∩ R) = A ∩ (T1 ∩ R)

Tactic:
by simp only [← Set.inter_assoc, Set.inter_comm _ A]

Goal state after:
Module: Mathlib.Order.Filter.AtTopBot.Finite

Goal state before:
pp: α : Type u_3
β : Type u_4
inst✝ : Preorder β
l : Filter α
p : β → Prop
f : α → β
hf : Tendsto f l atTop
h_evtl : ∀ᶠ (x : β) in atTop, p x
⊢ ∀ᶠ (x : α) in l, ∀ (y : β), f x ≤ y → p y

Tactic:
← Filter.eventually_forall_ge_atTop

Goal state after:
α : Type u_3
β : Type u_4
inst✝ : Preorder β
l : Filter α
p : β → Prop
f : α → β
hf : Tendsto f l atTop
h_evtl : ∀ᶠ (x : β) in atTop, ∀ (y : β), x ≤ y → p y
⊢ ∀ᶠ (x : α) in l, ∀ (y : β), f x ≤ y → p y
Module: Mathlib.Order.Filter.AtTopBot.CountablyGenerated

Goal state before:
pp: α : Type u_3
inst✝³ : Preorder α
inst✝² : Nonempty α
inst✝¹ : IsDirectedOrder α
inst✝ : atTop.IsCountablyGenerated
ys : ℕ → α
h : Tendsto ys atTop atTop
c : α → α → α
hleft : ∀ (a b : α), a ≤ c a b
hright : ∀ (a b : α), b ≤ c a b
xs : ℕ → α := fun n ↦ List.foldl (fun x n ↦ c x (ys n)) (ys 0) (List.range n)
hsucc : ∀ (n : ℕ), xs (n + 1) = c (xs n) (ys n)
⊢ ∃ xs, Monotone xs ∧ Tendsto xs atTop atTop

Tactic:
refine ⟨xs, ?_, ?_⟩

Goal state after:
case refine_1
α : Type u_3
inst✝³ : Preorder α
inst✝² : Nonempty α
inst✝¹ : IsDirectedOrder α
inst✝ : atTop.IsCountablyGenerated
ys : ℕ → α
h : Tendsto ys atTop atTop
c : α → α → α
hleft : ∀ (a b : α), a ≤ c a b
hright : ∀ (a b : α), b ≤ c a b
xs : ℕ → α := fun n ↦ List.foldl (fun x n ↦ c x (ys n)) (ys 0) (List.range n)
hsucc : ∀ (n : ℕ), xs (n + 1) = c (xs n) (ys n)
⊢ Monotone xs

case refine_2
α : Type u_3
inst✝³ : Preorder α
inst✝² : Nonempty α
inst✝¹ : IsDirectedOrder α
inst✝ : atTop.IsCountablyGenerated
ys : ℕ → α
h : Tendsto ys atTop atTop
c : α → α → α
hleft : ∀ (a b : α), a ≤ c a b
hright : ∀ (a b : α), b ≤ c a b
xs : ℕ → α := fun n ↦ List.foldl (fun x n ↦ c x (ys n)) (ys 0) (List.range n)
hsucc : ∀ (n : ℕ), xs (n + 1) = c (xs n) (ys n)
⊢ Tendsto xs atTop atTop
Module: Mathlib.Order.Filter.AtTopBot.CountablyGenerated

Goal state before:
pp: ι : Type u_3
l : Filter ι
p : ι → Prop
inst✝ : l.IsCountablyGenerated
⊢ (∀ᶠ (n : ι) in l, p n) ↔ ∀ (x : ℕ → ι), Tendsto x atTop l → ∀ᶠ (n : ℕ) in atTop, p (x n)

Tactic:
simpa using tendsto_iff_seq_tendsto (f := id) (l := 𝓟 {x | p x})

Goal state after:
Module: Mathlib.Algebra.Order.ToIntervalMod

Goal state before:
pp: α : Type u_1
inst✝² : AddCommGroup α
inst✝¹ : LinearOrder α
inst✝ : IsOrderedAddMonoid α
hα : Archimedean α
p : α
hp : 0 < p
a : α
⊢ toIocMod hp a a = a + p

Tactic:
rw [toIocMod_eq_iff hp, Set.right_mem_Ioc]

Goal state after:
α : Type u_1
inst✝² : AddCommGroup α
inst✝¹ : LinearOrder α
inst✝ : IsOrderedAddMonoid α
hα : Archimedean α
p : α
hp : 0 < p
a : α
⊢ a < a + p ∧ ∃ z, a = a + p + z • p