Theorem: AkraBazziRecurrence.eventually_one_add_smoothingFn_pos
File: Mathlib/Computability/AkraBazzi/AkraBazzi.lean

Proof steps:
state_before: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
⊢ ∀ᶠ (n : ℕ) in atTop, 0 < 1 + ε ↑n
state_after: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ε =o[atTop] fun x => 1
⊢ ∀ᶠ (n : ℕ) in atTop, 0 < 1 + ε ↑n
tactic: have h₁ := isLittleO_smoothingFn_one
state_before: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ε =o[atTop] fun x => 1
⊢ ∀ᶠ (n : ℕ) in atTop, 0 < 1 + ε ↑n
state_after: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
⊢ ∀ᶠ (n : ℕ) in atTop, 0 < 1 + ε ↑n
tactic: rw [isLittleO_iff] at h₁
state_before: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
⊢ ∀ᶠ (n : ℕ) in atTop, 0 < 1 + ε ↑n
state_after: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
⊢ ∀ᶠ (x : ℝ) in atTop, (fun n => 0 < 1 + ε n) x
tactic: refine Eventually.natCast_atTop (p := fun n => 0 < 1 + ε n) ?_
state_before: α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
⊢ ∀ᶠ (x : ℝ) in atTop, (fun n => 0 < 1 + ε n) x
state_after: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
⊢ 0 < 1 + ε x
tactic: filter_upwards [h₁ (by norm_num : (0 : ℝ) < 1/2), eventually_gt_atTop 1] with x _ hx'
state_before: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
⊢ 0 < 1 + ε x
state_after: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
this : 0 < log x
⊢ 0 < 1 + ε x
tactic: have : 0 < log x := Real.log_pos hx'
state_before: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
this : 0 < log x
⊢ 0 < 1 + ε x
state_after: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
this : 0 < log x
⊢ 0 < 1 + 1 / log x
tactic: show 0 < 1 + 1 / log x
state_before: case h
α : Type u_1
inst✝¹ : Fintype α
inst✝ : Nonempty α
T : ℕ → ℝ
g : ℝ → ℝ
a b : α → ℝ
r : α → ℕ → ℕ
R : AkraBazziRecurrence T g a b r
h₁ : ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ (x : ℝ) in atTop, ‖ε x‖ ≤ c * ‖1‖
x : ℝ
a✝ : ‖ε x‖ ≤ 1 / 2 * ‖1‖
hx' : 1 < x
this : 0 < log x
⊢ 0 < 1 + 1 / log x
state_after: no goals
tactic: positivity