-- Mathlib/Analysis/Normed/Ring/SmoothingSeminorm.lean
theorem tendsto_smoothingFun_of_ne_zero (hμ1 : μ 1 ≤ 1) {x : R} (hx : μ x ≠ 0) :
    Tendsto (smoothingSeminormSeq μ x) atTop (𝓝 (smoothingFun μ x))

Proof state:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
m2 : ℕ
hm2 : ∀ n ≥ m2, (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - 1 ≤ ε / (2 * (L + ε / 2))
n : ℕ
hn : n ≥ ↑m1 ⊔ m2
hn0 : 0 < n
hL_le : L ≤ smoothingSeminormSeq μ x n
hxn : ¬μ (x ^ (n % ↑m1)) = 0
hxn' : 0 < μ (x ^ (n % ↑m1))
h : μ (x ^ (↑m1 * (n / ↑m1))) ^ (1 / ↑n) ≤ (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n)
hL0'✝ : 0 < L + ε / 2
h1 : (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n) < (L + ε / 2) * (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n))
h2 : μ (x ^ (n % ↑m1)) ^ (1 / ↑n) ≤ (μ x ^ (n % ↑m1)) ^ (1 / ↑n)
heq : L + ε = L + ε / 2 + ε / 2
hL0' : 0 < L + ε / 2
⊢ (L + ε / 2) * (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - (L + ε / 2) ≤ ε / 2

Tactic:
nth_rw 3 [← mul_one (L + ε / 2)]

Result:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
m2 : ℕ
hm2 : ∀ n ≥ m2, (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - 1 ≤ ε / (2 * (L + ε / 2))
n : ℕ
hn : n ≥ ↑m1 ⊔ m2
hn0 : 0 < n
hL_le : L ≤ smoothingSeminormSeq μ x n
hxn : ¬μ (x ^ (n % ↑m1)) = 0
hxn' : 0 < μ (x ^ (n % ↑m1))
h : μ (x ^ (↑m1 * (n / ↑m1))) ^ (1 / ↑n) ≤ (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n)
hL0'✝ : 0 < L + ε / 2
h1 : (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n) < (L + ε / 2) * (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n))
h2 : μ (x ^ (n % ↑m1)) ^ (1 / ↑n) ≤ (μ x ^ (n % ↑m1)) ^ (1 / ↑n)
heq : L + ε = L + ε / 2 + ε / 2
hL0' : 0 < L + ε / 2
⊢ (L + ε / 2) * (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - (L + ε / 2) * 1 ≤ ε / 2

Proof state:
case h
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
m2 : ℕ
hm2 : ∀ n ≥ m2, (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - 1 ≤ ε / (2 * (L + ε / 2))
n : ℕ
hn : n ≥ ↑m1 ⊔ m2
hn0 : 0 < n
⊢ -ε < smoothingSeminormSeq μ x n - smoothingFun μ x ∧ smoothingSeminormSeq μ x n - smoothingFun μ x < ε

Tactic:
have hL_le : L ≤ smoothingSeminormSeq μ x n := by
  rw [← PNat.mk_coe n hn0]
  apply ciInf_le (smoothingSeminormSeq_bddBelow μ x)

Result:
case h
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
m2 : ℕ
hm2 : ∀ n ≥ m2, (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - 1 ≤ ε / (2 * (L + ε / 2))
n : ℕ
hn : n ≥ ↑m1 ⊔ m2
hn0 : 0 < n
hL_le : L ≤ smoothingSeminormSeq μ x n
⊢ -ε < smoothingSeminormSeq μ x n - smoothingFun μ x ∧ smoothingSeminormSeq μ x n - smoothingFun μ x < ε

Proof state:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
hε2 : 0 < ε / 2
hL2 : ∀ ε_1 > 0, ∃ N, ∀ n ≥ N, dist ((L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n)) 1 < ε_1
δ : ℝ := ε / (2 * (L + ε / 2))
hδ_def : δ = ε / (2 * (L + ε / 2))
⊢ 0 < ε / 2 * (1 / (L + ε / 2))

Tactic:
exact mul_pos hε2
  ((one_div (L + ε / 2)).symm ▸ inv_pos_of_pos (add_pos_of_nonneg_of_pos hL0 hε2))

Result:
no goals

Proof state:
case neg
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
m2 : ℕ
hm2 : ∀ n ≥ m2, (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n) - 1 ≤ ε / (2 * (L + ε / 2))
n : ℕ
hn : n ≥ ↑m1 ⊔ m2
hn0 : 0 < n
hL_le : L ≤ smoothingSeminormSeq μ x n
hxn : ¬μ (x ^ (n % ↑m1)) = 0
hxn' : 0 < μ (x ^ (n % ↑m1))
h : μ (x ^ (↑m1 * (n / ↑m1))) ^ (1 / ↑n) ≤ (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n)
hL0' : 0 < L + ε / 2
h1 : (μ (x ^ ↑m1) ^ (n / ↑m1)) ^ (1 / ↑n) < (L + ε / 2) * (L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n))
hnm1 : ¬n % ↑m1 = 0
⊢ μ (x ^ (n % ↑m1)) ^ (1 / ↑n) ≤ (μ x ^ (n % ↑m1)) ^ (1 / ↑n)

Tactic:
exact rpow_le_rpow (apply_nonneg μ _) (map_pow_le_pow μ _ hnm1) (one_div_cast_nonneg _)

Result:
no goals

Proof state:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
hε2 : 0 < ε / 2
hL2 : ∀ ε_1 > 0, ∃ N, ∀ n ≥ N, dist ((L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n)) 1 < ε_1
δ : ℝ := ε / (2 * (L + ε / 2))
hδ_def : δ = ε / (2 * (L + ε / 2))
⊢ 0 < δ

Tactic:
rw [hδ_def, div_mul_eq_div_mul_one_div]

Result:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
hε2 : 0 < ε / 2
hL2 : ∀ ε_1 > 0, ∃ N, ∀ n ≥ N, dist ((L + ε / 2) ^ (-(↑(n % ↑m1) / ↑n)) * (μ x ^ (n % ↑m1)) ^ (1 / ↑n)) 1 < ε_1
δ : ℝ := ε / (2 * (L + ε / 2))
hδ_def : δ = ε / (2 * (L + ε / 2))
⊢ 0 < ε / 2 * (1 / (L + ε / 2))

Proof state:
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
⊢ ∃ N, ∀ n ≥ N, dist (smoothingSeminormSeq μ x n) (smoothingFun μ x) < ε

Tactic:
obtain ⟨m1, hm1⟩ := smoothingSeminormSeq_exists_pnat μ x hε

Result:
case intro
R : Type u_1
inst✝ : CommRing R
μ : RingSeminorm R
hμ1 : μ 1 ≤ 1
x : R
hx : μ x ≠ 0
L : ℝ := ⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)
hL0 : 0 ≤ L
ε : ℝ
hε : ε > 0
m1 : ℕ+
hm1 : μ (x ^ ↑m1) ^ (1 / ↑↑m1) < (⨅ n, μ (x ^ ↑n) ^ (1 / ↑↑n)) + ε / 2
⊢ ∃ N, ∀ n ≥ N, dist (smoothingSeminormSeq μ x n) (smoothingFun μ x) < ε