refine hforall.mono ?_
case inl
b : ℕ∞
ha : ⊤ ≠ 0 ∨ b ≠ ⊤
hb : b ≠ 0 ∨ ⊤ ≠ ⊤
h : b ≤ ⊤
x : ℕ
hforall : ∀ᶠ (c : ℕ∞ × ℕ∞) in 𝓝 (⊤, b), ↑x < c.1 ∧ 0 < c.2
⊢ ∀ᶠ (a : ℕ∞ × ℕ∞) in 𝓝 (⊤, b), ↑x < a.1 * a.2
case inl
b : ℕ∞
ha : ⊤ ≠ 0 ∨ b ≠ ⊤
hb : b ≠ 0 ∨ ⊤ ≠ ⊤
h : b ≤ ⊤
x : ℕ
hforall : ∀ᶠ (c : ℕ∞ × ℕ∞) in 𝓝 (⊤, b), ↑x < c.1 ∧ 0 < c.2
⊢ ∀ (x_1 : ℕ∞ × ℕ∞), ↑x < x_1.1 ∧ 0 < x_1.2 → ↑x < x_1.1 * x_1.2