Module: Mathlib.RingTheory.Spectrum.Prime.ChevalleyComplexity

Goal state before:
pp: case refine_2
R₀ : Type u_1
inst✝² : CommRing R₀
n : ℕ
R : Type u_6
inst✝¹ : CommRing R
inst✝ : Algebra R₀ R
c : R
i : Fin n
e : InductionObj R n
hi : c = (e.val i).leadingCoeff
hc : c ≠ 0
q₁ : R →ₐ[R₀] Localization.Away c := IsScalarTower.toAlgHom R₀ R (Localization.Away c)
q₂ : R →ₐ[R₀] R ⧸ Ideal.span {c} := Ideal.Quotient.mkₐ R₀ (Ideal.span {c})
q₂_surjective : Surjective ⇑q₂
e₁ : InductionObj (Localization.Away c) n :=
  { val := Polynomial.C (IsLocalization.Away.invSelf c) • ⇑(mapRingHom ↑q₁) ∘ e.val }
e₂ : InductionObj (R ⧸ Ideal.span {c}) n := { val := ⇑(mapRingHom ↑q₂) ∘ e.val }
degBound_e₁_le : e₁.degBound ≤ e.degBound
degBound_e₂_lt : e₂.degBound < e.degBound
H₁ : Statement R₀ (Localization.Away c) n e₁
H₂ : Statement R₀ (R ⧸ Ideal.span {c}) n e₂
f : R[X]
T₁ : ConstructibleSetData (Localization.Away c)
T₂ : ConstructibleSetData (R ⧸ Ideal.span {c})
hT₁ : comap Polynomial.C '' (zeroLocus (Set.range e₁.val) \ zeroLocus {(mapRingHom ↑q₁) f}) = T₁.toSet
hT₁deg : ∀ x ∈ T₁, x.n ≤ e₁.degBound
hT₂ : comap Polynomial.C '' (zeroLocus (Set.range e₂.val) \ zeroLocus {(mapRingHom ↑q₂) f}) = T₂.toSet
hT₂deg : ∀ x ∈ T₂, x.n ≤ e₂.degBound
x✝ : Invertible (q₁ c) := { invOf := IsLocalization.Away.invSelf c, invOf_mul_self := ⋯, mul_invOf_self := ⋯ }
he₁span :
  coeffSubmodule R₀ e₁ ^ e₁.powBound =
    ⅟(q₁ c ^ e₁.powBound) • Submodule.map q₁.toLinearMap (span R₀ ({c} ∪ ⋃ i, coeff(e.val i)) ^ e₁.powBound)
g₁ : (x : BasicConstructibleSetData (Localization.Away c)) → Fin x.n → R
hg₁ : ∀ x ∈ T₁, ∀ (i : Fin x.n), g₁ x i ∈ ↑(span R₀ ({c} ∪ ⋃ i, coeff(e.val i)) ^ e₁.powBound)
hq₁g₁ : ∀ x ∈ T₁, ∀ (i : Fin x.n), q₁.toLinearMap (g₁ x i) = q₁ c ^ e₁.powBound * x.g i
n₁ : Localization.Away c → ℕ
f₁ : Localization.Away c → R
hf₁ : ∀ (x : Localization.Away c), x * q₁ c ^ n₁ x = q₁ (f₁ x)
g₂ : (x : BasicConstructibleSetData (R ⧸ Ideal.span {c})) → Fin x.n → R
hg₂ : ∀ x ∈ T₂, ∀ (i : Fin x.n), g₂ x i ∈ ↑(coeffSubmodule R₀ e ^ e₂.powBound)
hq₂g₂ : ∀ x ∈ T₂, ∀ (i : Fin x.n), q₂.toLinearMap (g₂ x i) = x.g i
f₂ : R ⧸ Ideal.span {c} → R
hf₂ : ∀ (x : R ⧸ Ideal.span {c}), q₂ (f₂ x) = x
S₁ : Finset (BasicConstructibleSetData R) := Finset.image (fun x ↦ { f := c * f₁ x.f, n := x.n, g := g₁ x }) T₁
S₂ : Finset (BasicConstructibleSetData R) :=
  Finset.image (fun x ↦ { f := f₂ x.f, n := x.n + 1, g := Fin.cons c (g₂ x) }) T₂
⊢ ∀ C ∈ S₁ ∪ S₂, C.n ≤ e.degBound ∧ ∀ (i : Fin C.n), C.g i ∈ coeffSubmodule R₀ e ^ e.powBound

Tactic:
· simp only [Finset.mem_union, forall_and, or_imp, Finset.forall_mem_image, S₁, S₂]
    refine ⟨⟨fun x hx ↦ (hT₁deg _ hx).trans degBound_e₁_le,
      fun x hx ↦ (hT₂deg _ hx).trans_lt degBound_e₂_lt⟩,
      fun x hx k ↦ SetLike.mem_of_subset ?_ (hg₁ _ hx _),
      fun x hx ↦ Fin.cons ?_ fun k ↦ SetLike.mem_of_subset ?_ (hg₂ _ hx _)⟩
    · norm_cast
      calc
        span R₀ ({c} ∪ ⋃ i, coeff(e i)) ^ e₁.powBound
        _ ≤ span R₀ (⋃ i, coeff(e i)) ^ e₁.powBound := by
          gcongr; simpa [Set.insert_subset_iff] using ⟨_, _, hi.symm⟩
        _ ≤ e.coeffSubmodule R₀ ^ e.powBound := by
          unfold coeffSubmodule powBound
          gcongr
          · exact one_le_coeffSubmodule
          · exact Set.subset_union_right
          · lia
    · exact le_self_pow one_le_coeffSubmodule powBound_ne_zero <| subset_span <| .inr <| by
        simpa using ⟨_, _, hi.symm⟩
    · unfold powBound
      gcongr
      · exact one_le_coeffSubmodule
      · lia

Goal state after: