mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.GroupTheory.Sylow

Goal state before:
pp: G : Type u
inst✝¹ : Group G
inst✝ : Finite G
p n : ℕ
hp : Fact (Nat.Prime p)
hdvd : p ^ (n + 1) ∣ Nat.card G
H : Subgroup G
hH : Nat.card ↥H = p ^ n
s : ℕ
hs : Nat.card G = s * p ^ (n + 1)
⊢ Nat.card (G ⧸ H) * Nat.card ↥H = s * p * Nat.card ↥H

Tactic:
← card_eq_card_quotient_mul_card_subgroup H,

Goal state after:
G : Type u
inst✝¹ : Group G
inst✝ : Finite G
p n : ℕ
hp : Fact (Nat.Prime p)
hdvd : p ^ (n + 1) ∣ Nat.card G
H : Subgroup G
hH : Nat.card ↥H = p ^ n
s : ℕ
hs : Nat.card G = s * p ^ (n + 1)
⊢ Nat.card G = s * p * Nat.card ↥H
Module: Mathlib.Order.CompactlyGenerated.Intervals

Goal state before:
pp: ι : Type u_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
a : α
x✝ : ↑(Iic a)
x : α
hx : x ≤ a
⊢ ∃ s, (∀ x ∈ s, IsCompactElement x) ∧ sSup s = ⟨x, hx⟩

Tactic:
obtain ⟨s, hs, rfl⟩ := IsCompactlyGenerated.exists_sSup_eq x

Goal state after:
ι : Type u_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
a : α
x✝ : ↑(Iic a)
s : Set α
hs : ∀ x ∈ s, IsCompactElement x
hx : sSup s ≤ a
⊢ ∃ s_1, (∀ x ∈ s_1, IsCompactElement x) ∧ sSup s_1 = ⟨sSup s, hx⟩
Module: Mathlib.RingTheory.SimpleModule.Basic

Goal state before:
pp: R : Type u_2
inst✝³ : Ring R
M : Type u_4
inst✝² : AddCommGroup M
inst✝¹ : Module R M
N : Submodule R M
inst✝ : IsSemisimpleModule R ↥N
⊢ N = ⊥ ∨ ∃ m ≤ N, IsSimpleModule R ↥m

Tactic:
by
  rw [← N.subsingleton_iff_eq_bot, ← Submodule.subsingleton_iff R, ← subsingleton_iff_bot_eq_top]
  refine (eq_bot_or_exists_atom_le _).imp .symm fun ⟨m, h, _⟩ ↦ ⟨_, N.map_subtype_le m, ?_⟩
  rw [← isSimpleModule_iff_isAtom] at h
  exact .congr (m.equivMapOfInjective _ N.subtype_injective).symm

Goal state after:
Module: Mathlib.RingTheory.SimpleModule.Basic

Goal state before:
pp: R : Type u_2
inst✝² : Ring R
M : Type u_4
inst✝¹ : AddCommGroup M
inst✝ : Module R M
p q : Submodule R M
x✝¹ : IsSemisimpleModule R ↥p
x✝ : IsSemisimpleModule R ↥q
f : Bool → Submodule R M := fun t ↦ Bool.rec q p t
⊢ p ⊔ q = ⨆ i ∈ Set.univ, f i

Tactic:
rw [iSup_univ, iSup_bool_eq]

Goal state after:
Module: Mathlib.RingTheory.SimpleModule.Basic

Goal state before:
pp: R : Type u_2
S : Type u_3
inst✝² : Ring R
inst✝¹ : Ring S
f : R →+* S
hf : Function.Surjective ⇑f
inst✝ : IsSemisimpleRing R
⊢ IsSemisimpleRing S

Tactic:
let : Module R S := Module.compHom _ f
  have : RingHomSurjective f := ⟨hf⟩
  let e : S →ₛₗ[f] S := { AddMonoidHom.id S with map_smul' := fun _ _ ↦ rfl }
  rw [IsSemisimpleRing, ← e.isSemisimpleModule_iff_of_bijective Function.bijective_id]
  infer_instance

Goal state after:
Module: Mathlib.RingTheory.SimpleModule.Basic

Goal state before:
pp: R : Type u_2
inst✝⁵ : Ring R
M : Type u_4
inst✝⁴ : AddCommGroup M
inst✝³ : Module R M
N : Type u_5
inst✝² : AddCommGroup N
inst✝¹ : Module R N
inst✝ : IsSimpleModule R N
f : M →ₗ[R] N
⊢ Function.Surjective ⇑f ∨ f = 0

Tactic:
by
  rw [← range_eq_top, ← range_eq_bot, or_comm]
  apply eq_bot_or_eq_top

Goal state after:
Module: Mathlib.Algebra.Module.Torsion.Basic

Goal state before:
pp: case h
R : Type u_1
M : Type u_2
inst✝⁵ : CommSemiring R
inst✝⁴ : AddCommMonoid M
inst✝³ : Module R M
S : Type u_3
inst✝² : CommMonoid S
inst✝¹ : DistribMulAction S M
inst✝ : SMulCommClass S R M
x y : M
a : S
hx : a • x = 0
b : S
hy : b • y = 0
⊢ (b * a) • (x + y) = 0

Tactic:
rw [smul_add, mul_smul, mul_comm, mul_smul, hx, hy, smul_zero, smul_zero, add_zero]

Goal state after:
Module: Mathlib.Algebra.Polynomial.Module.AEval

Goal state before:
pp: R : Type ?u.5
A : Type ?u.7
M : Type ?u.13
inst✝¹⁰ : CommSemiring R
inst✝⁹ : Semiring A
a : A
inst✝⁸ : Algebra R A
inst✝⁷ : AddCommMonoid M
inst✝⁶ : Module A M
inst✝⁵ : Module R M
inst✝⁴ : IsScalarTower R A M
N : Type ?u.26
inst✝³ : AddCommMonoid N
inst✝² : Module R N
inst✝¹ : Module R[X] N
inst✝ : IsScalarTower R R[X] N
f : M →ₗ[R] N
hf : ∀ (m : M), f (a • m) = X • f m
p : R[X]
n : ℕ
k : R
h :
  ∀ (x : AEval R M a),
    (f ∘ₗ ↑(of R M a).symm).toAddHom ((C k * X ^ n) • x) = (C k * X ^ n) • (f ∘ₗ ↑(of R M a).symm).toAddHom x
m : AEval R M a
⊢ (f ∘ₗ ↑(of R M a).symm).toAddHom ((C k * X ^ (n + 1)) • m) = (C k * X ^ (n + 1)) • (f ∘ₗ ↑(of R M a).symm).toAddHom m

Tactic:
LinearMap.coe_toAddHom,

Goal state after:
R : Type ?u.5
A : Type ?u.7
M : Type ?u.13
inst✝¹⁰ : CommSemiring R
inst✝⁹ : Semiring A
a : A
inst✝⁸ : Algebra R A
inst✝⁷ : AddCommMonoid M
inst✝⁶ : Module A M
inst✝⁵ : Module R M
inst✝⁴ : IsScalarTower R A M
N : Type ?u.26
inst✝³ : AddCommMonoid N
inst✝² : Module R N
inst✝¹ : Module R[X] N
inst✝ : IsScalarTower R R[X] N
f : M →ₗ[R] N
hf : ∀ (m : M), f (a • m) = X • f m
p : R[X]
n : ℕ
k : R
h : ∀ (x : AEval R M a), (f ∘ₗ ↑(of R M a).symm) ((C k * X ^ n) • x) = (C k * X ^ n) • (f ∘ₗ ↑(of R M a).symm) x
m : AEval R M a
⊢ (f ∘ₗ ↑(of R M a).symm) ((C k * X ^ (n + 1)) • m) = (C k * X ^ (n + 1)) • (f ∘ₗ ↑(of R M a).symm) m
Module: Mathlib.RingTheory.ReesAlgebra

Goal state before:
pp: case succ.refine_2
R : Type u
inst✝ : CommRing R
I : Ideal R
n : ℕ
hn : ∀ {r : R}, r ∈ I ^ n → (monomial n) r ∈ Algebra.adjoin R ↑(Submodule.map (monomial 1) I)
r : R
hr : r ∈ I * I ^ n
⊢ ∀ (x y : R),
    (monomial (n + 1)) x ∈ Algebra.adjoin R ↑(Submodule.map (monomial 1) I) →
      (monomial (n + 1)) y ∈ Algebra.adjoin R ↑(Submodule.map (monomial 1) I) →
        (monomial (n + 1)) (x + y) ∈ Algebra.adjoin R ↑(Submodule.map (monomial 1) I)

Tactic:
· intro x y hx hy
      rw [map_add]
      exact Subalgebra.add_mem _ hx hy

Goal state after:
Module: Mathlib.Algebra.Polynomial.Module.Basic

Goal state before:
pp: R : Type u_2
M : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : AddCommGroup M
inst✝⁶ : Module R M
R' : Type u_6
M' : Type u_7
inst✝⁵ : CommRing R'
inst✝⁴ : AddCommGroup M'
inst✝³ : Module R' M'
inst✝² : Module R M'
inst✝¹ : Algebra R R'
inst✝ : IsScalarTower R R' M'
f : M →ₗ[R] M'
q : PolynomialModule R M
r : R
⊢ (eval ((algebraMap R R') r)) ((map R' f) q) = f ((eval r) q)

Tactic:
by
  induction q using induction_linear with
  | zero => simp_rw [map_zero]
  | add f g e₁ e₂ => simp_rw [map_add, e₁, e₂]
  | single i m => simp only [map_single, eval_single, f.map_smul]; module

Goal state after:
Module: Mathlib.Algebra.Module.Torsion.Basic

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝² : CommSemiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
ι : Type u_3
S : Finset ι
q : ι → R
hq : (↑S).Pairwise (IsCoprime on q)
⊢ ⨆ i ∈ S, torsionBy R M (q i) = torsionBy R M (∏ i ∈ S, q i)

Tactic:
rw [← torsionBySet_span_singleton_eq, Ideal.submodule_span_eq, ←
    Ideal.finset_inf_span_singleton _ _ hq, Finset.inf_eq_iInf, ←
    iSup_torsionBySet_ideal_eq_torsionBySet_iInf]
  · congr
    ext : 1
    congr
    ext : 1
    exact (torsionBySet_span_singleton_eq _).symm
  exact fun i hi j hj ij => (Ideal.sup_eq_top_iff_isCoprime _ _).mpr (hq hi hj ij)

Goal state after:
Module: Mathlib.Algebra.Module.Torsion.Basic

Goal state before:
pp: G : Type u_3
inst✝ : AddCommGroup G
x : G
⊢ (∃ n, n ≠ 0 ∧ n • x = 0) ↔ x ∈ (torsion ℤ G).toAddSubgroup

Tactic:
simp [mem_nonZeroDivisors_iff_ne_zero]

Goal state after:
Module: Mathlib.Algebra.Category.ModuleCat.Differentials.Basic

Goal state before:
pp: A B : CommRingCat
f : A ⟶ B
M : ModuleCat ↑B
α β : KaehlerDifferential f ⟶ M
h : ∀ (b : ↑B), (ConcreteCategory.hom α) (d b) = (ConcreteCategory.hom β) (d b)
⊢ α = β

Tactic:
← sub_eq_zero

Goal state after:
A B : CommRingCat
f : A ⟶ B
M : ModuleCat ↑B
α β : KaehlerDifferential f ⟶ M
h : ∀ (b : ↑B), (ConcreteCategory.hom α) (d b) = (ConcreteCategory.hom β) (d b)
⊢ α - β = 0
Module: Mathlib.RingTheory.Ideal.Cotangent

Goal state before:
pp: R : Type u
inst✝ : CommRing R
I : Ideal R
x y : ↥I
⊢ I.toCotangent x = I.toCotangent y ↔ ↑x - ↑y ∈ I ^ 2

Tactic:
← sub_eq_zero

Goal state after:
R : Type u
inst✝ : CommRing R
I : Ideal R
x y : ↥I
⊢ I.toCotangent x - I.toCotangent y = 0 ↔ ↑x - ↑y ∈ I ^ 2
Module: Mathlib.RingTheory.Ideal.Cotangent

Goal state before:
pp: case h
A : Type u_1
B : Type u_2
inst✝² : CommRing A
inst✝¹ : CommRing B
inst✝ : Algebra A B
surj : Function.Surjective ⇑(algebraMap A B)
I : Ideal B
J : Ideal A
eq : comap (algebraMap A B) I = RingHom.ker (algebraMap A B) ⊔ J
x' : ↥I
y' : A
mem : y' ∈ J
hy' : (algebraMap A B) y' = ↑x'
⊢ (J.mapCotangent I (Algebra.ofId A B) ⋯) (J.toCotangent ⟨y', mem⟩) = I.toCotangent x'

Tactic:
simpa using I.toCotangent.congr_arg (SetCoe.ext hy')

Goal state after:
Module: Mathlib.Algebra.Category.ModuleCat.Differentials.Presheaf

Goal state before:
pp: C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
S : Cᵒᵖ ⥤ CommRingCat
F : C ⥤ D
S' R : Dᵒᵖ ⥤ CommRingCat
M N : PresheafOfModules (R ⋙ forget₂ CommRingCat RingCat)
φ : S ⟶ F.op ⋙ R
φ' : S' ⟶ R
x✝ : Dᵒᵖ
⊢ CommRingCat.KaehlerDifferential.map ⋯ =
    (ModuleCat.restrictScalarsId' (RingCat.Hom.hom ((R ⋙ forget₂ CommRingCat RingCat).map (𝟙 x✝))) ⋯).inv.app
      (CommRingCat.KaehlerDifferential (φ'.app x✝))

Tactic:
dsimp; ext; simp

Goal state after:
Module: Mathlib.Algebra.Category.ModuleCat.Differentials.Presheaf

Goal state before:
pp: C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
D : Type u₂
inst✝ : Category.{v₂, u₂} D
S : Cᵒᵖ ⥤ CommRingCat
F : C ⥤ D
S' R : Dᵒᵖ ⥤ CommRingCat
M N : PresheafOfModules (R ⋙ forget₂ CommRingCat RingCat)
φ : S ⟶ F.op ⋙ R
φ' : S' ⟶ R
X✝ Y✝ Z✝ : Dᵒᵖ
x✝¹ : X✝ ⟶ Y✝
x✝ : Y✝ ⟶ Z✝
⊢ CommRingCat.KaehlerDifferential.map ⋯ =
    CommRingCat.KaehlerDifferential.map ⋯ ≫
      (ModuleCat.restrictScalars (RingCat.Hom.hom ((R ⋙ forget₂ CommRingCat RingCat).map x✝¹))).map
          (CommRingCat.KaehlerDifferential.map ⋯) ≫
        (ModuleCat.restrictScalarsComp' (RingCat.Hom.hom ((R ⋙ forget₂ CommRingCat RingCat).map x✝¹))
                (RingCat.Hom.hom ((R ⋙ forget₂ CommRingCat RingCat).map x✝))
                (RingCat.Hom.hom ((R ⋙ forget₂ CommRingCat RingCat).map (x✝¹ ≫ x✝))) ⋯).inv.app
          (CommRingCat.KaehlerDifferential (φ'.app Z✝))

Tactic:
dsimp; ext; simp

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

Goal state before:
pp: case refine_1
ι : Type u_1
V : Type u
inst✝² : Category.{v, u} V
inst✝¹ : HasZeroMorphisms V
c : ComplexShape ι
inst✝ : HasZeroObject V
X : HomologicalComplex V c
f : zero ⟶ X
⊢ f = default

pp: case refine_2
ι : Type u_1
V : Type u
inst✝² : Category.{v, u} V
inst✝¹ : HasZeroMorphisms V
c : ComplexShape ι
inst✝ : HasZeroObject V
X : HomologicalComplex V c
f : X ⟶ zero
⊢ f = default

Tactic:
all_goals
    ext
    dsimp only [zero]
    subsingleton

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

Goal state before:
pp: V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : HasZeroMorphisms V
X₀ X₁ X₂ : V
d₀ : X₁ ⟶ X₀
d₁ : X₂ ⟶ X₁
s : d₁ ≫ d₀ = 0
succ : (S : ShortComplex V) → (X₃ : V) ×' (d₂ : X₃ ⟶ S.X₁) ×' d₂ ≫ S.f = 0
⊢ (mk X₀ X₁ X₂ d₀ d₁ s succ).d 2 1 = d₁

Tactic:
change ite (2 = 1 + 1) (𝟙 X₂ ≫ d₁) 0 = d₁

Goal state after:
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : HasZeroMorphisms V
X₀ X₁ X₂ : V
d₀ : X₁ ⟶ X₀
d₁ : X₂ ⟶ X₁
s : d₁ ≫ d₀ = 0
succ : (S : ShortComplex V) → (X₃ : V) ×' (d₂ : X₃ ⟶ S.X₁) ×' d₂ ≫ S.f = 0
⊢ (if 2 = 1 + 1 then 𝟙 X₂ ≫ d₁ else 0) = d₁
Module: Mathlib.Algebra.Homology.HomologicalComplex

Goal state before:
pp: case zero
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : HasZeroMorphisms V
X₀ X₁ X₂ : V
d₀ : X₁ ⟶ X₀
d₁ : X₂ ⟶ X₁
s : d₁ ≫ d₀ = 0
succ : (S : ShortComplex V) → (X₃ : V) ×' (d₂ : X₃ ⟶ S.X₁) ×' d₂ ≫ S.f = 0
succ' : {X₀ X₁ : V} → (f : X₁ ⟶ X₀) → (X₂ : V) ×' (d : X₂ ⟶ X₁) ×' d ≫ f = 0
⊢ (mk' X₀ X₁ d₀ fun {X₀ X₁} ↦ succ').X (0 + 2) = (succ' ((mk' X₀ X₁ d₀ fun {X₀ X₁} ↦ succ').d (0 + 1) 0)).fst

Tactic:
dsimp [mk', mk, of, mkAux, of.d]

Goal state after:
case zero
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : HasZeroMorphisms V
X₀ X₁ X₂ : V
d₀ : X₁ ⟶ X₀
d₁ : X₂ ⟶ X₁
s : d₁ ≫ d₀ = 0
succ : (S : ShortComplex V) → (X₃ : V) ×' (d₂ : X₃ ⟶ S.X₁) ×' d₂ ≫ S.f = 0
succ' : {X₀ X₁ : V} → (f : X₁ ⟶ X₀) → (X₂ : V) ×' (d : X₂ ⟶ X₁) ×' d ≫ f = 0
⊢ (succ' d₀).fst = (succ' (𝟙 X₁ ≫ d₀)).fst
Module: Mathlib.CategoryTheory.Shift.Basic

Goal state before:
pp: C : Type u
A : Type u_1
inst✝² : Category.{v, u} C
inst✝¹ : AddCommMonoid A
inst✝ : HasShift C A
X : C
n : A
⊢ (shiftFunctorZero C A).hom.app ((shiftFunctor C n).obj X) = (shiftFunctorAdd' C n 0 n ⋯).inv.app X

Tactic:
shiftFunctorAdd'_add_zero_inv_app

Goal state after:
C : Type u
A : Type u_1
inst✝² : Category.{v, u} C
inst✝¹ : AddCommMonoid A
inst✝ : HasShift C A
X : C
n : A
⊢ (shiftFunctorZero C A).hom.app ((shiftFunctor C n).obj X) = (shiftFunctorZero C A).hom.app ((shiftFunctor C n).obj X)
Module: Mathlib.RingTheory.Kaehler.Basic

Goal state before:
pp: case mp
R : Type u
S : Type v
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
f : S →ₐ[R] S ⊗[R] S ⧸ ideal R S ^ 2
x : S
e₁ :
  (TensorProduct.lmul' R).kerSquareLift (f x) =
    (quotientCotangentIdealRingEquiv R S) ((Ideal.Quotient.mk (ideal R S).cotangentIdeal) (f x))
e₂ :
  x =
    (quotientCotangentIdealRingEquiv R S)
      ((IsScalarTower.toAlgHom R S ((S ⊗[R] S ⧸ ideal R S ^ 2) ⧸ (ideal R S).cotangentIdeal)) x)
⊢ ((Ideal.Quotient.mkₐ R (ideal R S).cotangentIdeal).comp f) x =
      (IsScalarTower.toAlgHom R S ((S ⊗[R] S ⧸ ideal R S ^ 2) ⧸ (ideal R S).cotangentIdeal)) x →
    ((TensorProduct.lmul' R).kerSquareLift.comp f) x = (AlgHom.id R S) x

Tactic:
intro e
    exact (e₁.trans (@RingEquiv.congr_arg _ _ _ _ _ _
      (KaehlerDifferential.quotientCotangentIdealRingEquiv R S) _ _ e)).trans e₂.symm

Goal state after:
Module: Mathlib.RingTheory.Kaehler.Basic

Goal state before:
pp: R : Type u
inst✝⁶ : CommRing R
A : Type u_2
B : Type u_3
inst✝⁵ : CommRing A
inst✝⁴ : CommRing B
inst✝³ : Algebra R A
inst✝² : Algebra A B
inst✝¹ : Algebra R B
inst✝ : IsScalarTower R A B
h : Function.Surjective ⇑(algebraMap A B)
⊢ Submodule.map (linearCombination A ⇑(D R A))
      (Submodule.comap (mapRange.linearMap (Algebra.linearMap A B) ∘ₗ lmapDomain A A ⇑(algebraMap A B))
        (Submodule.map (mapRange.linearMap (Algebra.linearMap A B) ∘ₗ lmapDomain A A ⇑(algebraMap A B))
          (kerTotal R A ⊔ Submodule.span A (Set.range fun x ↦ single ((algebraMap R A) x) 1)))) =
    Submodule.map (linearCombination A ⇑(D R A))
      (mapRange.linearMap (Algebra.linearMap A B) ∘ₗ lmapDomain A A ⇑(algebraMap A B)).ker

Tactic:
Submodule.comap_map_eq,

Goal state after:
R : Type u
inst✝⁶ : CommRing R
A : Type u_2
B : Type u_3
inst✝⁵ : CommRing A
inst✝⁴ : CommRing B
inst✝³ : Algebra R A
inst✝² : Algebra A B
inst✝¹ : Algebra R B
inst✝ : IsScalarTower R A B
h : Function.Surjective ⇑(algebraMap A B)
⊢ Submodule.map (linearCombination A ⇑(D R A))
      (kerTotal R A ⊔ Submodule.span A (Set.range fun x ↦ single ((algebraMap R A) x) 1) ⊔
        (mapRange.linearMap (Algebra.linearMap A B) ∘ₗ lmapDomain A A ⇑(algebraMap A B)).ker) =
    Submodule.map (linearCombination A ⇑(D R A))
      (mapRange.linearMap (Algebra.linearMap A B) ∘ₗ lmapDomain A A ⇑(algebraMap A B)).ker
Module: Mathlib.Algebra.Homology.Homotopy

Goal state before:
pp: case e_a.succ
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i : ι
P Q : ChainComplex V ℕ
e : P ⟶ Q
zero : P.X 0 ⟶ Q.X 1
comm_zero : e.f 0 = zero ≫ Q.d 1 0
one : P.X 1 ⟶ Q.X 2
comm_one : e.f 1 = P.d 1 0 ≫ zero + one ≫ Q.d 2 1
succ :
  (n : ℕ) →
    (p :
        (f : P.X n ⟶ Q.X (n + 1)) ×'
          (f' : P.X (n + 1) ⟶ Q.X (n + 2)) ×' e.f (n + 1) = P.d (n + 1) n ≫ f + f' ≫ Q.d (n + 2) (n + 1)) →
      (f'' : P.X (n + 2) ⟶ Q.X (n + 3)) ×' e.f (n + 2) = P.d (n + 2) (n + 1) ≫ p.snd.fst + f'' ≫ Q.d (n + 3) (n + 2)
n✝ : ℕ
⊢ (xNextIso P ⋯).hom ≫ (mkInductiveAux₁ e zero one comm_one succ n✝).fst =
    if h : (ComplexShape.down ℕ).next (n✝ + 1) + 1 = n✝ + 1 then
      (mkInductiveAux₂ e zero comm_zero one comm_one succ ((ComplexShape.down ℕ).next (n✝ + 1))).snd.fst ≫
        (xPrevIso Q h).hom
    else 0

Tactic:
simp only [ChainComplex.next_nat_succ, dite_true]

Goal state after:
case e_a.succ
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i : ι
P Q : ChainComplex V ℕ
e : P ⟶ Q
zero : P.X 0 ⟶ Q.X 1
comm_zero : e.f 0 = zero ≫ Q.d 1 0
one : P.X 1 ⟶ Q.X 2
comm_one : e.f 1 = P.d 1 0 ≫ zero + one ≫ Q.d 2 1
succ :
  (n : ℕ) →
    (p :
        (f : P.X n ⟶ Q.X (n + 1)) ×'
          (f' : P.X (n + 1) ⟶ Q.X (n + 2)) ×' e.f (n + 1) = P.d (n + 1) n ≫ f + f' ≫ Q.d (n + 2) (n + 1)) →
      (f'' : P.X (n + 2) ⟶ Q.X (n + 3)) ×' e.f (n + 2) = P.d (n + 2) (n + 1) ≫ p.snd.fst + f'' ≫ Q.d (n + 3) (n + 2)
n✝ : ℕ
⊢ (xNextIso P ⋯).hom ≫ (mkInductiveAux₁ e zero one comm_one succ n✝).fst =
    (mkInductiveAux₂ e zero comm_zero one comm_one succ ((ComplexShape.down ℕ).next (n✝ + 1))).snd.fst ≫
      (xPrevIso Q ⋯).hom
Module: Mathlib.Algebra.Homology.Homotopy

Goal state before:
pp: case e_a.e_a
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i✝ : ι
P Q : ChainComplex V ℕ
e : P ⟶ Q
zero : P.X 0 ⟶ Q.X 1
comm_zero : e.f 0 = zero ≫ Q.d 1 0
one : P.X 1 ⟶ Q.X 2
comm_one : e.f 1 = P.d 1 0 ≫ zero + one ≫ Q.d 2 1
succ :
  (n : ℕ) →
    (p :
        (f : P.X n ⟶ Q.X (n + 1)) ×'
          (f' : P.X (n + 1) ⟶ Q.X (n + 2)) ×' e.f (n + 1) = P.d (n + 1) n ≫ f + f' ≫ Q.d (n + 2) (n + 1)) →
      (f'' : P.X (n + 2) ⟶ Q.X (n + 3)) ×' e.f (n + 2) = P.d (n + 2) (n + 1) ≫ p.snd.fst + f'' ≫ Q.d (n + 3) (n + 2)
i : ℕ
⊢ (mkInductiveAux₂ e zero comm_zero one comm_one succ i).snd.fst =
    (toPrev i) fun i j ↦
      if h : i + 1 = j then (mkInductiveAux₂ e zero comm_zero one comm_one succ i).snd.fst ≫ (xPrevIso Q h).hom else 0

Tactic:
dsimp [toPrev]

Goal state after:
case e_a.e_a
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i✝ : ι
P Q : ChainComplex V ℕ
e : P ⟶ Q
zero : P.X 0 ⟶ Q.X 1
comm_zero : e.f 0 = zero ≫ Q.d 1 0
one : P.X 1 ⟶ Q.X 2
comm_one : e.f 1 = P.d 1 0 ≫ zero + one ≫ Q.d 2 1
succ :
  (n : ℕ) →
    (p :
        (f : P.X n ⟶ Q.X (n + 1)) ×'
          (f' : P.X (n + 1) ⟶ Q.X (n + 2)) ×' e.f (n + 1) = P.d (n + 1) n ≫ f + f' ≫ Q.d (n + 2) (n + 1)) →
      (f'' : P.X (n + 2) ⟶ Q.X (n + 3)) ×' e.f (n + 2) = P.d (n + 2) (n + 1) ≫ p.snd.fst + f'' ≫ Q.d (n + 3) (n + 2)
i : ℕ
⊢ (mkInductiveAux₂ e zero comm_zero one comm_one succ i).snd.fst =
    if h : i + 1 = (ComplexShape.down ℕ).prev i then
      (mkInductiveAux₂ e zero comm_zero one comm_one succ i).snd.fst ≫ (xPrevIso Q h).hom
    else 0
Module: Mathlib.Algebra.Homology.HomotopyCofiber

Goal state before:
pp: case pos
C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝¹ : HasHomotopyCofiber φ
inst✝ : DecidableRel c.Rel
H : ∀ (j : ι), ∃ i, c.Rel i j
i : ι
hi : c.Rel i (c.next i)
⊢ (mapArrowHom φ φ H (𝟙 (Arrow.mk φ))).f i = 𝟙 (X φ i)

pp: case neg
C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝¹ : HasHomotopyCofiber φ
inst✝ : DecidableRel c.Rel
H : ∀ (j : ι), ∃ i, c.Rel i j
i : ι
hi : ¬c.Rel i (c.next i)
⊢ (mapArrowHom φ φ H (𝟙 (Arrow.mk φ))).f i = 𝟙 (X φ i)

Tactic:
· refine ext_to_X _ _ _ hi ?_ ?_
    all_goals simp [mapArrowHom, desc_f _ _ _ _ _ hi, inrCompHomotopy_hom _ _ _ _ hi]

Goal state after:
case neg
C : Type u_1
inst✝³ : Category.{v_1, u_1} C
inst✝² : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝¹ : HasHomotopyCofiber φ
inst✝ : DecidableRel c.Rel
H : ∀ (j : ι), ∃ i, c.Rel i j
i : ι
hi : ¬c.Rel i (c.next i)
⊢ (mapArrowHom φ φ H (𝟙 (Arrow.mk φ))).f i = 𝟙 (X φ i)
Module: Mathlib.Algebra.Homology.HomotopyCofiber

Goal state before:
pp: case pos
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝³ : HasHomotopyCofiber φ
inst✝² : DecidableRel c.Rel
F' F'' G' G'' : HomologicalComplex C c
φ' : F' ⟶ G'
φ'' : F'' ⟶ G''
inst✝¹ : HasHomotopyCofiber φ'
inst✝ : HasHomotopyCofiber φ''
H : ∀ (j : ι), ∃ i, c.Rel i j
α : Arrow.mk φ ⟶ Arrow.mk φ'
β : Arrow.mk φ' ⟶ Arrow.mk φ''
i : ι
hi : c.Rel i (c.next i)
⊢ (mapArrowHom φ φ'' H (α ≫ β)).f i = (mapArrowHom φ φ' H α).f i ≫ (mapArrowHom φ' φ'' H β).f i

pp: case neg
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝³ : HasHomotopyCofiber φ
inst✝² : DecidableRel c.Rel
F' F'' G' G'' : HomologicalComplex C c
φ' : F' ⟶ G'
φ'' : F'' ⟶ G''
inst✝¹ : HasHomotopyCofiber φ'
inst✝ : HasHomotopyCofiber φ''
H : ∀ (j : ι), ∃ i, c.Rel i j
α : Arrow.mk φ ⟶ Arrow.mk φ'
β : Arrow.mk φ' ⟶ Arrow.mk φ''
i : ι
hi : ¬c.Rel i (c.next i)
⊢ (mapArrowHom φ φ'' H (α ≫ β)).f i = (mapArrowHom φ φ' H α).f i ≫ (mapArrowHom φ' φ'' H β).f i

Tactic:
· refine ext_to_X _ _ _ hi ?_ ?_
    all_goals simp [mapArrowHom, desc_f _ _ _ _ _ hi, inrCompHomotopy_hom _ _ _ _ hi]

Goal state after:
case neg
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : Preadditive C
ι : Type u_2
c : ComplexShape ι
F G : HomologicalComplex C c
φ : F ⟶ G
inst✝³ : HasHomotopyCofiber φ
inst✝² : DecidableRel c.Rel
F' F'' G' G'' : HomologicalComplex C c
φ' : F' ⟶ G'
φ'' : F'' ⟶ G''
inst✝¹ : HasHomotopyCofiber φ'
inst✝ : HasHomotopyCofiber φ''
H : ∀ (j : ι), ∃ i, c.Rel i j
α : Arrow.mk φ ⟶ Arrow.mk φ'
β : Arrow.mk φ' ⟶ Arrow.mk φ''
i : ι
hi : ¬c.Rel i (c.next i)
⊢ (mapArrowHom φ φ'' H (α ≫ β)).f i = (mapArrowHom φ φ' H α).f i ≫ (mapArrowHom φ' φ'' H β).f i
Module: Mathlib.Algebra.Homology.Homotopy

Goal state before:
pp: case e_a.e_a.succ
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i : ι
P Q : CochainComplex V ℕ
e : P ⟶ Q
zero : P.X 1 ⟶ Q.X 0
comm_zero : e.f 0 = P.d 0 1 ≫ zero
one : P.X 2 ⟶ Q.X 1
comm_one : e.f 1 = zero ≫ Q.d 0 1 + P.d 1 2 ≫ one
succ :
  (n : ℕ) →
    (p :
        (f : P.X (n + 1) ⟶ Q.X n) ×'
          (f' : P.X (n + 2) ⟶ Q.X (n + 1)) ×' e.f (n + 1) = f ≫ Q.d n (n + 1) + P.d (n + 1) (n + 2) ≫ f') →
      (f'' : P.X (n + 3) ⟶ Q.X (n + 2)) ×' e.f (n + 2) = p.snd.fst ≫ Q.d (n + 1) (n + 2) + P.d (n + 2) (n + 3) ≫ f''
n✝ : ℕ
⊢ (mkCoinductiveAux₂ e zero comm_zero one comm_one succ (n✝ + 1)).fst =
    (toPrev (n✝ + 1)) fun i j ↦
      if h : j + 1 = i then (xNextIso P h).inv ≫ (mkCoinductiveAux₂ e zero comm_zero one comm_one succ j).snd.fst else 0

Tactic:
dsimp [toPrev]

Goal state after:
case e_a.e_a.succ
ι : Type u_1
V : Type u
inst✝¹ : Category.{v, u} V
inst✝ : Preadditive V
c : ComplexShape ι
C D E : HomologicalComplex V c
f g : C ⟶ D
h k : D ⟶ E
i : ι
P Q : CochainComplex V ℕ
e : P ⟶ Q
zero : P.X 1 ⟶ Q.X 0
comm_zero : e.f 0 = P.d 0 1 ≫ zero
one : P.X 2 ⟶ Q.X 1
comm_one : e.f 1 = zero ≫ Q.d 0 1 + P.d 1 2 ≫ one
succ :
  (n : ℕ) →
    (p :
        (f : P.X (n + 1) ⟶ Q.X n) ×'
          (f' : P.X (n + 2) ⟶ Q.X (n + 1)) ×' e.f (n + 1) = f ≫ Q.d n (n + 1) + P.d (n + 1) (n + 2) ≫ f') →
      (f'' : P.X (n + 3) ⟶ Q.X (n + 2)) ×' e.f (n + 2) = p.snd.fst ≫ Q.d (n + 1) (n + 2) + P.d (n + 2) (n + 3) ≫ f''
n✝ : ℕ
⊢ (mkCoinductiveAux₁ e zero one comm_one succ n✝).fst ≫ (xPrevIso Q ⋯).inv =
    if h : (ComplexShape.up ℕ).prev (n✝ + 1) + 1 = n✝ + 1 then
      (xNextIso P h).inv ≫
        (mkCoinductiveAux₂ e zero comm_zero one comm_one succ ((ComplexShape.up ℕ).prev (n✝ + 1))).snd.fst
    else 0
Module: Mathlib.Algebra.Homology.Homotopy

Goal state before:
pp: case pos
ι✝ : Type u_1
V : Type u
inst✝⁴ : Category.{v, u} V
inst✝³ : Preadditive V
c✝ : ComplexShape ι✝
C✝ D E : HomologicalComplex V c✝
f✝ g✝ : C✝ ⟶ D
h✝ k : D ⟶ E
i✝ : ι✝
C : Type u_2
inst✝² : Category.{v_1, u_2} C
inst✝¹ : Preadditive C
ι : Type ?u.42
c : ComplexShape ι
inst✝ : DecidableRel c.Rel
K L : HomologicalComplex C c
f g : K ⟶ L
ho : Homotopy f g
i : ι
h : c.Rel (c.prev i) i
⊢ f.f (c.prev i) =
    K.d (c.prev i) i ≫ ho.hom i (c.prev i) +
        ho.hom (c.prev i) (c.prev (c.prev i)) ≫ L.d (c.prev (c.prev i)) (c.prev i) +
      g.f (c.prev i)

Tactic:
rw [ho.comm (c.prev i)]
      dsimp [dFrom, dTo, fromNext, toPrev]
      rw [congr_arg (fun j => d K (c.prev i) j ≫ ho.hom j (c.prev i)) (c.next_eq' h)]

Goal state after: