English
For each m, the function n ↦ ack m n is strictly increasing.
Русский
Для каждого m функция n ↦ ack(m,n) строго возрастает.
LaTeX
$$$$\forall m\in\mathbb{N},\ \text{StrictMono}(n \mapsto \operatorname{ack}(m,n)).$$$$
Lean4
theorem ack_strictMono_right : ∀ m, StrictMono (ack m)
| 0, n₁, n₂, h => by simpa using h
| m + 1, 0, n + 1, _h => by
rw [ack_succ_zero, ack_succ_succ]
exact ack_strictMono_right _ (one_lt_ack_succ_left m n)
| m + 1, n₁ + 1, n₂ + 1, h => by
rw [ack_succ_succ, ack_succ_succ]
apply ack_strictMono_right _ (ack_strictMono_right _ _)
rwa [add_lt_add_iff_right] at h