Module: Mathlib.RingTheory.Localization.Integral

Goal state before:
pp: case refine_1.refine_2
R : Type u_1
inst✝² : CommRing R
S : Type u_2
inst✝¹ : CommRing S
inst✝ : Algebra R S
t s : S
hst : s * t = 1
ht : IsIntegral (↥R[s]) t
a✝ : Nontrivial S
φ : R[X] →ₐ[R] S := aeval s
q : R[X][X]
hqm : q.Monic
hqt : eval₂ φ.toRingHom t q = 0
N : ℕ := q.support.sup fun x ↦ (q.coeff x).natDegree
hN : ∀ (i : ℕ), (q.coeff i).natDegree ≤ N
q' : R[X] := q.sum fun i r ↦ X ^ i * reflect N r
this : ∀ (i : ℕ), (aeval t) (reflect N (q.coeff i)) = t ^ N * (aeval s) (q.coeff i)
⊢ (if q.natDegree ≤ q.natDegree + N then (q.coeff q.natDegree).coeff ((revAt N) (q.natDegree + N - q.natDegree))
    else 0) =
    1

pp: case refine_1.refine_2.h₀
R : Type u_1
inst✝² : CommRing R
S : Type u_2
inst✝¹ : CommRing S
inst✝ : Algebra R S
t s : S
hst : s * t = 1
ht : IsIntegral (↥R[s]) t
a✝ : Nontrivial S
φ : R[X] →ₐ[R] S := aeval s
q : R[X][X]
hqm : q.Monic
hqt : eval₂ φ.toRingHom t q = 0
N : ℕ := q.support.sup fun x ↦ (q.coeff x).natDegree
hN : ∀ (i : ℕ), (q.coeff i).natDegree ≤ N
q' : R[X] := q.sum fun i r ↦ X ^ i * reflect N r
this : ∀ (i : ℕ), (aeval t) (reflect N (q.coeff i)) = t ^ N * (aeval s) (q.coeff i)
⊢ ∀ b ∈ q.support,
    b ≠ q.natDegree → (if b ≤ q.natDegree + N then (q.coeff b).coeff ((revAt N) (q.natDegree + N - b)) else 0) = 0

pp: case refine_1.refine_2.h₁
R : Type u_1
inst✝² : CommRing R
S : Type u_2
inst✝¹ : CommRing S
inst✝ : Algebra R S
t s : S
hst : s * t = 1
ht : IsIntegral (↥R[s]) t
a✝ : Nontrivial S
φ : R[X] →ₐ[R] S := aeval s
q : R[X][X]
hqm : q.Monic
hqt : eval₂ φ.toRingHom t q = 0
N : ℕ := q.support.sup fun x ↦ (q.coeff x).natDegree
hN : ∀ (i : ℕ), (q.coeff i).natDegree ≤ N
q' : R[X] := q.sum fun i r ↦ X ^ i * reflect N r
this : ∀ (i : ℕ), (aeval t) (reflect N (q.coeff i)) = t ^ N * (aeval s) (q.coeff i)
⊢ q.natDegree ∉ q.support →
    (if q.natDegree ≤ q.natDegree + N then (q.coeff q.natDegree).coeff ((revAt N) (q.natDegree + N - q.natDegree))
      else 0) =
      0

Tactic:
· simp [hqm.leadingCoeff]

Goal state after:
case refine_1.refine_2.h₀
R : Type u_1
inst✝² : CommRing R
S : Type u_2
inst✝¹ : CommRing S
inst✝ : Algebra R S
t s : S
hst : s * t = 1
ht : IsIntegral (↥R[s]) t
a✝ : Nontrivial S
φ : R[X] →ₐ[R] S := aeval s
q : R[X][X]
hqm : q.Monic
hqt : eval₂ φ.toRingHom t q = 0
N : ℕ := q.support.sup fun x ↦ (q.coeff x).natDegree
hN : ∀ (i : ℕ), (q.coeff i).natDegree ≤ N
q' : R[X] := q.sum fun i r ↦ X ^ i * reflect N r
this : ∀ (i : ℕ), (aeval t) (reflect N (q.coeff i)) = t ^ N * (aeval s) (q.coeff i)
⊢ ∀ b ∈ q.support,
    b ≠ q.natDegree → (if b ≤ q.natDegree + N then (q.coeff b).coeff ((revAt N) (q.natDegree + N - b)) else 0) = 0

case refine_1.refine_2.h₁
R : Type u_1
inst✝² : CommRing R
S : Type u_2
inst✝¹ : CommRing S
inst✝ : Algebra R S
t s : S
hst : s * t = 1
ht : IsIntegral (↥R[s]) t
a✝ : Nontrivial S
φ : R[X] →ₐ[R] S := aeval s
q : R[X][X]
hqm : q.Monic
hqt : eval₂ φ.toRingHom t q = 0
N : ℕ := q.support.sup fun x ↦ (q.coeff x).natDegree
hN : ∀ (i : ℕ), (q.coeff i).natDegree ≤ N
q' : R[X] := q.sum fun i r ↦ X ^ i * reflect N r
this : ∀ (i : ℕ), (aeval t) (reflect N (q.coeff i)) = t ^ N * (aeval s) (q.coeff i)
⊢ q.natDegree ∉ q.support →
    (if q.natDegree ≤ q.natDegree + N then (q.coeff q.natDegree).coeff ((revAt N) (q.natDegree + N - q.natDegree))
      else 0) =
      0