English
IsPreirreducible is preserved by closure: IsPreirreducible(closure s) iff IsPreirreducible(s).
Русский
Неразложимость сохраняется при замыкании: IsPreirreducible(closure s) ⇔ IsPreirreducible(s).
LaTeX
$$$\\operatorname{IsPreirreducible}(\\overline{s}) \\iff \\operatorname{IsPreirreducible}(s)$$$
Lean4
theorem isPreirreducible_iff_closure : IsPreirreducible (closure s) ↔ IsPreirreducible s :=
forall₄_congr fun u v hu hv => by
iterate 3 rw [closure_inter_open_nonempty_iff]
exacts [hu.inter hv, hv, hu]