English
Irreducible p ⇔ (¬IsUnit p) ∧ ∀ a,b, p = a*b → IsUnit a ∨ IsUnit b.
Русский
Неразложимый p эквивалентно: не единица и для любых a,b, p = a b → IsUnit a ∨ IsUnit b.
LaTeX
$$$\\text{Irreducible } p \\Leftrightarrow (\\neg IsUnit\\ p) \\land \\forall\\{a,b\\},\\ p = a b \\Rightarrow IsUnit\\ a \\lor IsUnit\\ b$$$
Lean4
@[to_additive]
theorem irreducible_iff : Irreducible p ↔ ¬IsUnit p ∧ ∀ ⦃a b⦄, p = a * b → IsUnit a ∨ IsUnit b
where
mp hp := ⟨hp.not_isUnit, hp.isUnit_or_isUnit⟩
mpr hp := ⟨hp.1, hp.2⟩