English
A filter is disjoint from cocompact iff it contains a compact set.
Русский
Фильтр не пересекается с кокомпактным тогда и только тогда, когда он содержит компактное множество.
LaTeX
$$$\operatorname{Disjoint}(f, \operatorname{cocompact}(X)) \iff \exists K \in f, \operatorname{IsCompact}(K)$$$
Lean4
/-- A filter is disjoint from the cocompact filter if and only if it contains a compact set. -/
theorem disjoint_cocompact_right (f : Filter X) : Disjoint f (Filter.cocompact X) ↔ ∃ K ∈ f, IsCompact K :=
by
simp_rw [hasBasis_cocompact.disjoint_iff_right, compl_compl]
tauto