l3lab/ntp-mathlib huggingface dataset:
theorem derivative_rootMultiplicity_of_root_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} (hpt : Polynomial.IsRoot p t)
    (hnzd : (p.rootMultiplicity t : R) ∈ nonZeroDivisors R) :
    (derivative p).rootMultiplicity t = p.rootMultiplicity t - 1 := by
  by_cases h : p = 0
  · simp only [h, map_zero, rootMultiplicity_zero]
  obtain ⟨g, hp, hndvd⟩ := p.exists_eq_pow_rootMultiplicity_mul_and_not_dvd h t
  set m := p.rootMultiplicity t
  have hm : m - 1 + 1 = m := Nat.sub_add_cancel <| (rootMultiplicity_pos h).2 hpt
  have hndvd : ¬(X - C t) ^ m ∣ derivative p := by
    rw [hp, derivative_mul, dvd_add_left (dvd_mul_right _ _),
      derivative_X_sub_C_pow, ← hm, pow_succ', hm, mul_comm (C _), mul_assoc,
      dvd_cancel_left_mem_nonZeroDivisors (monic_X_sub_C t |>.pow _ |>.mem_nonZeroDivisors)]
    rw [dvd_iff_isRoot, IsRoot] at hndvd ⊢
    rwa [eval_mul, eval_C, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd]
  

Proof state:
case neg.intro.intro
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
hpt : IsRoot p t
h : ¬p = 0
g : R[X]
hndvd✝ : ¬X - C t ∣ g
m : ℕ := rootMultiplicity t p
hnzd : ↑m ∈ nonZeroDivisors R
hp : p = (X - C t) ^ m * g
hm : m - 1 + 1 = m
hndvd : ¬(X - C t) ^ m ∣ derivative p
⊢ rootMultiplicity t (derivative p) = m - 1

Next tactic:
have hnezero : derivative p ≠ 0 := fun h ↦ hndvd (by rw [h]; exact dvd_zero _)
theorem derivative_rootMultiplicity_of_root_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} (hpt : Polynomial.IsRoot p t)
    (hnzd : (p.rootMultiplicity t : R) ∈ nonZeroDivisors R) :
    (derivative p).rootMultiplicity t = p.rootMultiplicity t - 1 := by
  by_cases h : p = 0
  · simp only [h, map_zero, rootMultiplicity_zero]
  obtain ⟨g, hp, hndvd⟩ := p.exists_eq_pow_rootMultiplicity_mul_and_not_dvd h t
  set m := p.rootMultiplicity t
  have hm : m - 1 + 1 = m := Nat.sub_add_cancel <| (rootMultiplicity_pos h).2 hpt
  have hndvd : ¬(X - C t) ^ m ∣ derivative p := by
    rw [hp, derivative_mul, dvd_add_left (dvd_mul_right _ _),
      derivative_X_sub_C_pow, ← hm, pow_succ', hm, mul_comm (C _), mul_assoc,
      dvd_cancel_left_mem_nonZeroDivisors (monic_X_sub_C t |>.pow _ |>.mem_nonZeroDivisors)]
    rw [dvd_iff_isRoot, IsRoot] at hndvd ⊢
    rwa [eval_mul, eval_C, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd]
  have hnezero : derivative p ≠ 0 := fun h ↦ hndvd (by 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
hpt : IsRoot p t
h✝ : ¬p = 0
g : R[X]
hndvd✝ : ¬X - C t ∣ g
m : ℕ := rootMultiplicity t p
hnzd : ↑m ∈ nonZeroDivisors R
hp : p = (X - C t) ^ m * g
hm : m - 1 + 1 = m
hndvd : ¬(X - C t) ^ m ∣ derivative p
h : derivative p = 0
⊢ (X - C t) ^ m ∣ derivative p

Next tactic:
rw [h]
theorem derivative_rootMultiplicity_of_root_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} (hpt : Polynomial.IsRoot p t)
    (hnzd : (p.rootMultiplicity t : R) ∈ nonZeroDivisors R) :
    (derivative p).rootMultiplicity t = p.rootMultiplicity t - 1 := by
  by_cases h : p = 0
  · simp only [h, map_zero, rootMultiplicity_zero]
  obtain ⟨g, hp, hndvd⟩ := p.exists_eq_pow_rootMultiplicity_mul_and_not_dvd h t
  set m := p.rootMultiplicity t
  have hm : m - 1 + 1 = m := Nat.sub_add_cancel <| (rootMultiplicity_pos h).2 hpt
  have hndvd : ¬(X - C t) ^ m ∣ derivative p := by
    rw [hp, derivative_mul, dvd_add_left (dvd_mul_right _ _),
      derivative_X_sub_C_pow, ← hm, pow_succ', hm, mul_comm (C _), mul_assoc,
      dvd_cancel_left_mem_nonZeroDivisors (monic_X_sub_C t |>.pow _ |>.mem_nonZeroDivisors)]
    rw [dvd_iff_isRoot, IsRoot] at hndvd ⊢
    rwa [eval_mul, eval_C, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd]
  have hnezero : derivative p ≠ 0 := fun h ↦ hndvd (by rw [h]; 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
hpt : IsRoot p t
h✝ : ¬p = 0
g : R[X]
hndvd✝ : ¬X - C t ∣ g
m : ℕ := rootMultiplicity t p
hnzd : ↑m ∈ nonZeroDivisors R
hp : p = (X - C t) ^ m * g
hm : m - 1 + 1 = m
hndvd : ¬(X - C t) ^ m ∣ derivative p
h : derivative p = 0
⊢ (X - C t) ^ m ∣ 0

Next tactic:
exact dvd_zero _
theorem derivative_rootMultiplicity_of_root_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} (hpt : Polynomial.IsRoot p t)
    (hnzd : (p.rootMultiplicity t : R) ∈ nonZeroDivisors R) :
    (derivative p).rootMultiplicity t = p.rootMultiplicity t - 1 := by
  by_cases h : p = 0
  · simp only [h, map_zero, rootMultiplicity_zero]
  obtain ⟨g, hp, hndvd⟩ := p.exists_eq_pow_rootMultiplicity_mul_and_not_dvd h t
  set m := p.rootMultiplicity t
  have hm : m - 1 + 1 = m := Nat.sub_add_cancel <| (rootMultiplicity_pos h).2 hpt
  have hndvd : ¬(X - C t) ^ m ∣ derivative p := by
    rw [hp, derivative_mul, dvd_add_left (dvd_mul_right _ _),
      derivative_X_sub_C_pow, ← hm, pow_succ', hm, mul_comm (C _), mul_assoc,
      dvd_cancel_left_mem_nonZeroDivisors (monic_X_sub_C t |>.pow _ |>.mem_nonZeroDivisors)]
    rw [dvd_iff_isRoot, IsRoot] at hndvd ⊢
    rwa [eval_mul, eval_C, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd]
  have hnezero : derivative p ≠ 0 := fun h ↦ hndvd (by rw [h]; exact dvd_zero _)
  

Proof state:
case neg.intro.intro
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
hpt : IsRoot p t
h : ¬p = 0
g : R[X]
hndvd✝ : ¬X - C t ∣ g
m : ℕ := rootMultiplicity t p
hnzd : ↑m ∈ nonZeroDivisors R
hp : p = (X - C t) ^ m * g
hm : m - 1 + 1 = m
hndvd : ¬(X - C t) ^ m ∣ derivative p
hnezero : derivative p ≠ 0
⊢ rootMultiplicity t (derivative p) = m - 1

Next tactic:
exact le_antisymm (by rwa [rootMultiplicity_le_iff hnezero, hm])
    (rootMultiplicity_sub_one_le_derivative_rootMultiplicity_of_ne_zero _ t hnezero)
theorem derivative_rootMultiplicity_of_root_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} (hpt : Polynomial.IsRoot p t)
    (hnzd : (p.rootMultiplicity t : R) ∈ nonZeroDivisors R) :
    (derivative p).rootMultiplicity t = p.rootMultiplicity t - 1 := by
  by_cases h : p = 0
  · simp only [h, map_zero, rootMultiplicity_zero]
  obtain ⟨g, hp, hndvd⟩ := p.exists_eq_pow_rootMultiplicity_mul_and_not_dvd h t
  set m := p.rootMultiplicity t
  have hm : m - 1 + 1 = m := Nat.sub_add_cancel <| (rootMultiplicity_pos h).2 hpt
  have hndvd : ¬(X - C t) ^ m ∣ derivative p := by
    rw [hp, derivative_mul, dvd_add_left (dvd_mul_right _ _),
      derivative_X_sub_C_pow, ← hm, pow_succ', hm, mul_comm (C _), mul_assoc,
      dvd_cancel_left_mem_nonZeroDivisors (monic_X_sub_C t |>.pow _ |>.mem_nonZeroDivisors)]
    rw [dvd_iff_isRoot, IsRoot] at hndvd ⊢
    rwa [eval_mul, eval_C, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd]
  have hnezero : derivative p ≠ 0 := fun h ↦ hndvd (by rw [h]; exact dvd_zero _)
  exact le_antisymm (by 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
hpt : IsRoot p t
h : ¬p = 0
g : R[X]
hndvd✝ : ¬X - C t ∣ g
m : ℕ := rootMultiplicity t p
hnzd : ↑m ∈ nonZeroDivisors R
hp : p = (X - C t) ^ m * g
hm : m - 1 + 1 = m
hndvd : ¬(X - C t) ^ m ∣ derivative p
hnezero : derivative p ≠ 0
⊢ rootMultiplicity t (derivative p) ≤ m - 1

Next tactic:
rwa [rootMultiplicity_le_iff hnezero, hm]
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
⊢ eval t ((⇑derivative)^[rootMultiplicity t p] p) =
    Nat.factorial (rootMultiplicity t p) • eval t (p /ₘ (X - C t) ^ rootMultiplicity t p)

Next tactic:
set m := p.rootMultiplicity t with hm
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
⊢ eval t ((⇑derivative)^[m] p) = Nat.factorial m • eval t (p /ₘ (X - C t) ^ m)

Next tactic:
conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
| eval t ((⇑derivative)^[m] p)

Next tactic:
rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
⊢ eval t ((⇑derivative)^[m] ((X - C t) ^ m * (p /ₘ (X - C t) ^ m))) = Nat.factorial m • eval t (p /ₘ (X - C t) ^ m)

Next tactic:
rw [iterate_derivative_mul, eval_finset_sum, sum_eq_single_of_mem _ (mem_range.mpr m.succ_pos)]
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
  rw [iterate_derivative_mul, eval_finset_sum, sum_eq_single_of_mem _ (mem_range.mpr m.succ_pos)]
  · 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
⊢ eval t (Nat.choose m 0 • ((⇑derivative)^[m - 0] ((X - C t) ^ m) * (⇑derivative)^[0] (p /ₘ (X - C t) ^ m))) =
    Nat.factorial m • eval t (p /ₘ (X - C t) ^ m)

Next tactic:
rw [m.choose_zero_right, one_smul, eval_mul, m.sub_zero, iterate_derivative_X_sub_pow_self,
      eval_nat_cast, nsmul_eq_mul]
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
  rw [iterate_derivative_mul, eval_finset_sum, sum_eq_single_of_mem _ (mem_range.mpr m.succ_pos)]
  · rw [m.choose_zero_right, one_smul, eval_mul, m.sub_zero, iterate_derivative_X_sub_pow_self,
      eval_nat_cast, nsmul_eq_mul]; 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
⊢ ↑(Nat.factorial m) * eval t ((⇑derivative)^[0] (p /ₘ (X - C t) ^ m)) =
    ↑(Nat.factorial m) * eval t (p /ₘ (X - C t) ^ m)

Next tactic:
rfl
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
  rw [iterate_derivative_mul, eval_finset_sum, sum_eq_single_of_mem _ (mem_range.mpr m.succ_pos)]
  · rw [m.choose_zero_right, one_smul, eval_mul, m.sub_zero, iterate_derivative_X_sub_pow_self,
      eval_nat_cast, nsmul_eq_mul]; rfl
  · 

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
⊢ ∀ b ∈ range (Nat.succ m),
    b ≠ 0 →
      eval t (Nat.choose m b • ((⇑derivative)^[m - b] ((X - C t) ^ m) * (⇑derivative)^[b] (p /ₘ (X - C t) ^ m))) = 0

Next tactic:
intro b hb hb0
open Finset in
theorem eval_iterate_derivative_rootMultiplicity {p : R[X]} {t : R} :
    (derivative^[p.rootMultiplicity t] p).eval t =
      (p.rootMultiplicity t).factorial • (p /ₘ (X - C t) ^ p.rootMultiplicity t).eval t := by
  set m := p.rootMultiplicity t with hm
  conv_lhs => rw [← p.pow_mul_divByMonic_rootMultiplicity_eq t, ← hm]
  rw [iterate_derivative_mul, eval_finset_sum, sum_eq_single_of_mem _ (mem_range.mpr m.succ_pos)]
  · rw [m.choose_zero_right, one_smul, eval_mul, m.sub_zero, iterate_derivative_X_sub_pow_self,
      eval_nat_cast, nsmul_eq_mul]; rfl
  · intro b hb hb0
    

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b✝ : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
m : ℕ := rootMultiplicity t p
hm : m = rootMultiplicity t p
b : ℕ
hb : b ∈ range (Nat.succ m)
hb0 : b ≠ 0
⊢ eval t (Nat.choose m b • ((⇑derivative)^[m - b] ((X - C t) ^ m) * (⇑derivative)^[b] (p /ₘ (X - C t) ^ m))) = 0

Next tactic:
rw [iterate_derivative_X_sub_pow, eval_smul, eval_mul, eval_smul, eval_pow,
      Nat.sub_sub_self (mem_range_succ_iff.mp hb), eval_sub, eval_X, eval_C, sub_self,
      zero_pow' b hb0, smul_zero, zero_mul, smul_zero]
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hroot : ∀ m ≤ n, IsRoot ((⇑derivative)^[m] p) t
hnzd : ↑(Nat.factorial n) ∈ nonZeroDivisors R
⊢ n < rootMultiplicity t p

Next tactic:
by_contra! h'
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hroot : ∀ m ≤ n, IsRoot ((⇑derivative)^[m] p) t
hnzd : ↑(Nat.factorial n) ∈ nonZeroDivisors R
h' : rootMultiplicity t p ≤ n
⊢ False

Next tactic:
replace hroot := hroot _ h'
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  replace hroot := hroot _ h'
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hnzd : ↑(Nat.factorial n) ∈ nonZeroDivisors R
h' : rootMultiplicity t p ≤ n
hroot : IsRoot ((⇑derivative)^[rootMultiplicity t p] p) t
⊢ False

Next tactic:
simp only [IsRoot, eval_iterate_derivative_rootMultiplicity] at hroot
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  replace hroot := hroot _ h'
  simp only [IsRoot, eval_iterate_derivative_rootMultiplicity] at hroot
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hnzd : ↑(Nat.factorial n) ∈ nonZeroDivisors R
h' : rootMultiplicity t p ≤ n
hroot : Nat.factorial (rootMultiplicity t p) • eval t (p /ₘ (X - C t) ^ rootMultiplicity t p) = 0
⊢ False

Next tactic:
obtain ⟨q, hq⟩ := Nat.coe_nat_dvd (α := R) <| Nat.factorial_dvd_factorial h'
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  replace hroot := hroot _ h'
  simp only [IsRoot, eval_iterate_derivative_rootMultiplicity] at hroot
  obtain ⟨q, hq⟩ := Nat.coe_nat_dvd (α := R) <| Nat.factorial_dvd_factorial h'
  

Proof state:
case intro
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hnzd : ↑(Nat.factorial n) ∈ nonZeroDivisors R
h' : rootMultiplicity t p ≤ n
hroot : Nat.factorial (rootMultiplicity t p) • eval t (p /ₘ (X - C t) ^ rootMultiplicity t p) = 0
q : R
hq : ↑(Nat.factorial n) = ↑(Nat.factorial (rootMultiplicity t p)) * q
⊢ False

Next tactic:
rw [hq, mul_mem_nonZeroDivisors] at hnzd
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  replace hroot := hroot _ h'
  simp only [IsRoot, eval_iterate_derivative_rootMultiplicity] at hroot
  obtain ⟨q, hq⟩ := Nat.coe_nat_dvd (α := R) <| Nat.factorial_dvd_factorial h'
  rw [hq, mul_mem_nonZeroDivisors] at hnzd
  

Proof state:
case intro
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
h' : rootMultiplicity t p ≤ n
hroot : Nat.factorial (rootMultiplicity t p) • eval t (p /ₘ (X - C t) ^ rootMultiplicity t p) = 0
q : R
hnzd : ↑(Nat.factorial (rootMultiplicity t p)) ∈ nonZeroDivisors R ∧ q ∈ nonZeroDivisors R
hq : ↑(Nat.factorial n) = ↑(Nat.factorial (rootMultiplicity t p)) * q
⊢ False

Next tactic:
rw [nsmul_eq_mul, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd.1] at hroot
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : (n.factorial : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  by_contra! h'
  replace hroot := hroot _ h'
  simp only [IsRoot, eval_iterate_derivative_rootMultiplicity] at hroot
  obtain ⟨q, hq⟩ := Nat.coe_nat_dvd (α := R) <| Nat.factorial_dvd_factorial h'
  rw [hq, mul_mem_nonZeroDivisors] at hnzd
  rw [nsmul_eq_mul, mul_left_mem_nonZeroDivisors_eq_zero_iff hnzd.1] at hroot
  

Proof state:
case intro
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
h' : rootMultiplicity t p ≤ n
hroot : eval t (p /ₘ (X - C t) ^ rootMultiplicity t p) = 0
q : R
hnzd : ↑(Nat.factorial (rootMultiplicity t p)) ∈ nonZeroDivisors R ∧ q ∈ nonZeroDivisors R
hq : ↑(Nat.factorial n) = ↑(Nat.factorial (rootMultiplicity t p)) * q
⊢ False

Next tactic:
exact eval_divByMonic_pow_rootMultiplicity_ne_zero t h hroot
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hroot : ∀ m ≤ n, IsRoot ((⇑derivative)^[m] p) t
hnzd : ∀ m ≤ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ n < rootMultiplicity t p

Next tactic:
apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hroot : ∀ m ≤ n, IsRoot ((⇑derivative)^[m] p) t
hnzd : ∀ m ≤ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ ↑(Nat.factorial n) ∈ nonZeroDivisors R

Next tactic:
clear hroot
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  clear hroot
  

Proof state:
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
n : ℕ
h : p ≠ 0
hnzd : ∀ m ≤ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ ↑(Nat.factorial n) ∈ nonZeroDivisors R

Next tactic:
induction' n with n ih
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  clear hroot
  induction' n with n ih
  · 

Proof state:
case zero
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
h : p ≠ 0
hnzd : ∀ m ≤ Nat.zero, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ ↑(Nat.factorial Nat.zero) ∈ nonZeroDivisors R

Next tactic:
simp only [Nat.zero_eq, Nat.factorial_zero, Nat.cast_one]
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  clear hroot
  induction' n with n ih
  · simp only [Nat.zero_eq, Nat.factorial_zero, Nat.cast_one]
    

Proof state:
case zero
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n : ℕ
inst✝ : CommRing R
p : R[X]
t : R
h : p ≠ 0
hnzd : ∀ m ≤ Nat.zero, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ 1 ∈ nonZeroDivisors R

Next tactic:
exact Submonoid.one_mem _
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  clear hroot
  induction' n with n ih
  · simp only [Nat.zero_eq, Nat.factorial_zero, Nat.cast_one]
    exact Submonoid.one_mem _
  · 

Proof state:
case succ
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
h : p ≠ 0
n : ℕ
ih : (∀ m ≤ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R) → ↑(Nat.factorial n) ∈ nonZeroDivisors R
hnzd : ∀ m ≤ Nat.succ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ ↑(Nat.factorial (Nat.succ n)) ∈ nonZeroDivisors R

Next tactic:
rw [Nat.factorial_succ, Nat.cast_mul, mul_mem_nonZeroDivisors]
theorem lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors'
    {p : R[X]} {t : R} {n : ℕ} (h : p ≠ 0)
    (hroot : ∀ m ≤ n, (derivative^[m] p).IsRoot t)
    (hnzd : ∀ m ≤ n, m ≠ 0 → (m : R) ∈ nonZeroDivisors R) :
    n < p.rootMultiplicity t := by
  apply lt_rootMultiplicity_of_isRoot_iterate_derivative_of_mem_nonZeroDivisors h hroot
  clear hroot
  induction' n with n ih
  · simp only [Nat.zero_eq, Nat.factorial_zero, Nat.cast_one]
    exact Submonoid.one_mem _
  · rw [Nat.factorial_succ, Nat.cast_mul, mul_mem_nonZeroDivisors]
    

Proof state:
case succ
R : Type u
S : Type v
k : Type y
A : Type z
a b : R
n✝ : ℕ
inst✝ : CommRing R
p : R[X]
t : R
h : p ≠ 0
n : ℕ
ih : (∀ m ≤ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R) → ↑(Nat.factorial n) ∈ nonZeroDivisors R
hnzd : ∀ m ≤ Nat.succ n, m ≠ 0 → ↑m ∈ nonZeroDivisors R
⊢ ↑(n + 1) ∈ nonZeroDivisors R ∧ ↑(Nat.factorial n) ∈ nonZeroDivisors R

Next tactic:
exact ⟨hnzd _ le_rfl n.succ_ne_zero, ih fun m h ↦ hnzd m (h.trans n.le_succ)⟩