Theorem: _private.Mathlib.RingTheory.MvPolynomial.Homogeneous.0.MvPolynomial.IsHomogeneous.exists_eval_ne_zero_of_coeff_finSuccEquiv_ne_zero_aux
File: Mathlib/RingTheory/MvPolynomial/Homogeneous.lean

Proof steps:
state_before: σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
⊢ ∃ r, (eval r) F ≠ 0
state_after: σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
⊢ ∃ r, (eval r) F ≠ 0
tactic: have hF₀ : F ≠ 0 := by contrapose! hFn; simp [hFn]
state_before: σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
⊢ ∃ r, (eval r) F ≠ 0
state_after: σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
⊢ ∃ r, (eval r) F ≠ 0
tactic: have hdeg : natDegree (finSuccEquiv R N F) < n + 1 := by
    linarith [natDegree_finSuccEquiv F, degreeOf_le_totalDegree F 0, hF.totalDegree hF₀]
state_before: σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
⊢ ∃ r, (eval r) F ≠ 0
state_after: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
⊢ (eval (Fin.cons 1 0)) F ≠ 0
tactic: use Fin.cons 1 0
state_before: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
⊢ (eval (Fin.cons 1 0)) F ≠ 0
state_after: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
⊢ (eval (Fin.cons 1 0)) F ≠ 0
tactic: have aux : ∀ i ∈ Finset.range n, constantCoeff ((finSuccEquiv R N F).coeff i) = 0 := by
    intro i hi
    rw [Finset.mem_range] at hi
    apply (hF.finSuccEquiv_coeff_isHomogeneous i (n-i) (by omega)).coeff_eq_zero
    simp only [Finsupp.degree_zero]
    rw [← Nat.sub_ne_zero_iff_lt] at hi
    exact hi.symm
state_before: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
⊢ (eval (Fin.cons 1 0)) F ≠ 0
state_after: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
⊢ constantCoeff (((finSuccEquiv R N) F).coeff n) ≠ 0
tactic: simp_rw [eval_eq_eval_mv_eval', eval_one_map, Polynomial.eval_eq_sum_range' hdeg,
    eval_zero, one_pow, mul_one, map_sum, Finset.sum_range_succ, Finset.sum_eq_zero aux, zero_add]
state_before: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hFn : ((finSuccEquiv R N) F).coeff n ≠ 0
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
⊢ constantCoeff (((finSuccEquiv R N) F).coeff n) ≠ 0
state_after: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
⊢ ((finSuccEquiv R N) F).coeff n = 0
tactic: contrapose! hFn
state_before: case h
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
⊢ ((finSuccEquiv R N) F).coeff n = 0
state_after: case h.a
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
d : Fin N →₀ ℕ
⊢ coeff d (((finSuccEquiv R N) F).coeff n) = coeff d 0
tactic: ext d
state_before: case h.a
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
d : Fin N →₀ ℕ
⊢ coeff d (((finSuccEquiv R N) F).coeff n) = coeff d 0
state_after: case h.a
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
d : Fin N →₀ ℕ
⊢ coeff d (((finSuccEquiv R N) F).coeff n) = 0
tactic: rw [coeff_zero]
state_before: case h.a
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
d : Fin N →₀ ℕ
⊢ coeff d (((finSuccEquiv R N) F).coeff n) = 0
state_after: case h.a.inl
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
⊢ coeff 0 (((finSuccEquiv R N) F).coeff n) = 0

case h.a.inr
σ : Type u_1
τ : Type u_2
R : Type u_3
S : Type u_4
inst✝² inst✝¹ : CommSemiring R
inst✝ : CommSemiring S
φ ψ : MvPolynomial σ R
m n✝ N : ℕ
F : MvPolynomial (Fin N.succ) R
n : ℕ
hF : F.IsHomogeneous n
hF₀ : F ≠ 0
hdeg : ((finSuccEquiv R N) F).natDegree < n + 1
aux : ∀ i ∈ Finset.range n, constantCoeff (((finSuccEquiv R N) F).coeff i) = 0
hFn : constantCoeff (((finSuccEquiv R N) F).coeff n) = 0
d : Fin N →₀ ℕ
hd : d ≠ 0
⊢ coeff d (((finSuccEquiv R N) F).coeff n) = 0
tactic: obtain rfl | hd := eq_or_ne d 0