English
In a monoid, for any natural number n ≠ 1, the element x^n is not irreducible.
Русский
В моноиде для любого натурального числа n ≠ 1 элемент x^n не является неразложимым.
LaTeX
$$$\\\\forall {n : \\\\mathbb{N}}, n \\\\neq 1 \\\\rightarrow \\\\neg Irreducible (x^n)$$$
Lean4
@[to_additive]
theorem not_irreducible_pow : ∀ {n : ℕ}, n ≠ 1 → ¬Irreducible (x ^ n)
| 0, _ => by simp
| n + 2, _ => by
intro ⟨h₁, h₂⟩
have := h₂ (pow_succ _ _)
rw [isUnit_pow_iff n.succ_ne_zero, or_self] at this
exact h₁ (this.pow _)