English
In a Nontrivial α, for any p ∈ FactorSet α, p.prod = 0 if and only if p = ⊤.
Русский
В немножко различном α для любого p ∈ FactorSet α произведение p равно 0 тогда и только тогда, когда p = вершина (⊤).
LaTeX
$$$[\text{Nontrivial }\alpha]\ (p \in \mathrm{FactorSet}(\alpha)) \Rightarrow (p.prod = 0 \iff p = \top).$$$
Lean4
theorem prod_eq_zero_iff [Nontrivial α] (p : FactorSet α) : p.prod = 0 ↔ p = ⊤ :=
by
unfold FactorSet at p
induction p
· simp only [Associates.prod_top]
· rw [prod_coe, Multiset.prod_eq_zero_iff, Multiset.mem_map, eq_false WithTop.coe_ne_top, iff_false, not_exists]
exact fun a => not_and_of_not_right _ a.prop.ne_zero