Module: Mathlib.AlgebraicGeometry.Modules.Tilde

Goal state before:
pp: case refine_1
R : CommRingCat
M : (Spec R).Modules
g : ↑R
a : R ⟶ CommRingCat.of (Localization.Away g) := CommRingCat.ofHom (algebraMap (↑R) (Localization.Away g))
ψ : Spec (CommRingCat.of (Localization.Away g)) ⟶ Spec (CommRingCat.of ↑R) := Spec.map a
M' : (Spec (CommRingCat.of (Localization.Away g))).Modules := M.restrict ψ
h : Aux M' ⊤
heq : ∀ (f : ↑R), basicOpen f ≤ basicOpen g → basicOpen f = ψ ''ᵁ basicOpen ((ConcreteCategory.hom a) f)
iso : Γ(M.restrict ψ, ⊤) ≅ Γ(M, basicOpen g) :=
  Scheme.Modules.restrictAppIso ψ M ⊤ ≪≫ Functor.mapIso M.presheaf (eqToIso ⋯).op
e : (f : ↑R) → basicOpen f ≤ basicOpen g → (Γ(M', basicOpen ((ConcreteCategory.hom a) f)) ≅ Γ(M, basicOpen f)) :=
  fun f hf ↦
    Scheme.Modules.restrictAppIso ψ M (basicOpen ((ConcreteCategory.hom a) f)) ≪≫
      Functor.mapIso M.presheaf (eqToIso ⋯).op
f : ↑R
hf : basicOpen f ≤ basicOpen g
s : ↑Γ(M, basicOpen f)
⊢ ∃ n t, (ConcreteCategory.hom (M.presheaf.map (homOfLE hf).op)) t = f ^ n • s

pp: case refine_2
R : CommRingCat
M : (Spec R).Modules
g : ↑R
a : R ⟶ CommRingCat.of (Localization.Away g) := CommRingCat.ofHom (algebraMap (↑R) (Localization.Away g))
ψ : Spec (CommRingCat.of (Localization.Away g)) ⟶ Spec (CommRingCat.of ↑R) := Spec.map a
M' : (Spec (CommRingCat.of (Localization.Away g))).Modules := M.restrict ψ
h : Aux M' ⊤
heq : ∀ (f : ↑R), basicOpen f ≤ basicOpen g → basicOpen f = ψ ''ᵁ basicOpen ((ConcreteCategory.hom a) f)
iso : Γ(M.restrict ψ, ⊤) ≅ Γ(M, basicOpen g) :=
  Scheme.Modules.restrictAppIso ψ M ⊤ ≪≫ Functor.mapIso M.presheaf (eqToIso ⋯).op
e : (f : ↑R) → basicOpen f ≤ basicOpen g → (Γ(M', basicOpen ((ConcreteCategory.hom a) f)) ≅ Γ(M, basicOpen f)) :=
  fun f hf ↦
    Scheme.Modules.restrictAppIso ψ M (basicOpen ((ConcreteCategory.hom a) f)) ≪≫
      Functor.mapIso M.presheaf (eqToIso ⋯).op
f : ↑R
hf : basicOpen f ≤ basicOpen g
t : ↑Γ(M, basicOpen g)
ht : (ConcreteCategory.hom (M.presheaf.map (homOfLE hf).op)) t = 0
⊢ ∃ n, f ^ n • t = 0

Tactic:
· obtain ⟨n, t, ht⟩ := h.existence (a f) le_top ((e _ hf).inv s)
    use n, iso.hom t
    have := congr((e _ hf).hom $ht)
    dsimp [M'] at this
    rw [← ConcreteCategory.comp_apply] at this
    simp only [homOfLE_leOfHom, Iso.trans_hom, Functor.mapIso_hom, Iso.op_hom, eqToIso.hom,
      eqToHom_op, Iso.trans_inv, Functor.mapIso_inv, Iso.op_inv, eqToIso.inv, e, iso] at this ⊢
    simp only [homOfLE_leOfHom, Scheme.Modules.map_restrictAppIso_hom_assoc, AddCommGrpCat.hom_comp,
      AddMonoidHom.coe_comp, Function.comp_apply, ← map_pow, ψ] at this
    rw [Scheme.Modules.restrictAppIso_smul_Spec] at this
    simpa [← Functor.map_comp_apply, eqToHom_comp_homOfLE_op, homOfLE_op_comp_eqToHom] using this

Goal state after:
case refine_2
R : CommRingCat
M : (Spec R).Modules
g : ↑R
a : R ⟶ CommRingCat.of (Localization.Away g) := CommRingCat.ofHom (algebraMap (↑R) (Localization.Away g))
ψ : Spec (CommRingCat.of (Localization.Away g)) ⟶ Spec (CommRingCat.of ↑R) := Spec.map a
M' : (Spec (CommRingCat.of (Localization.Away g))).Modules := M.restrict ψ
h : Aux M' ⊤
heq : ∀ (f : ↑R), basicOpen f ≤ basicOpen g → basicOpen f = ψ ''ᵁ basicOpen ((ConcreteCategory.hom a) f)
iso : Γ(M.restrict ψ, ⊤) ≅ Γ(M, basicOpen g) :=
  Scheme.Modules.restrictAppIso ψ M ⊤ ≪≫ Functor.mapIso M.presheaf (eqToIso ⋯).op
e : (f : ↑R) → basicOpen f ≤ basicOpen g → (Γ(M', basicOpen ((ConcreteCategory.hom a) f)) ≅ Γ(M, basicOpen f)) :=
  fun f hf ↦
    Scheme.Modules.restrictAppIso ψ M (basicOpen ((ConcreteCategory.hom a) f)) ≪≫
      Functor.mapIso M.presheaf (eqToIso ⋯).op
f : ↑R
hf : basicOpen f ≤ basicOpen g
t : ↑Γ(M, basicOpen g)
ht : (ConcreteCategory.hom (M.presheaf.map (homOfLE hf).op)) t = 0
⊢ ∃ n, f ^ n • t = 0