obtain ⟨N, hu⟩ := eventually_atTop.mp hu
n : ℕ
A a b c d u✝ x y t σ' : ℝ
ψ Ψ : ℝ → ℂ
F G : ℂ → ℂ
f : ℕ → ℂ
𝕜 : Type
inst✝ : _root_.RCLike 𝕜
u : ℕ → ℝ
hu : ∀ᶠ (n : ℕ) in atTop, 0 ≤ u n
⊢ Summable u ↔ atTop.BoundedAtFilter (cumsum u)
case intro
n : ℕ
A a b c d u✝ x y t σ' : ℝ
ψ Ψ : ℝ → ℂ
F G : ℂ → ℂ
f : ℕ → ℂ
𝕜 : Type
inst✝ : _root_.RCLike 𝕜
u : ℕ → ℝ
hu✝ : ∀ᶠ (n : ℕ) in atTop, 0 ≤ u n
N : ℕ
hu : ∀ b ≥ N, 0 ≤ u b
⊢ Summable u ↔ atTop.BoundedAtFilter (cumsum u)