Filter on a set
= Filter on a set
{wiki=Filter_(set_theory)}
A filter $\mathcal F$ on a set $X$ is a nonempty family of subsets that excludes the empty set, is closed under finite intersections, and is upward closed under inclusion.
= Filter on a set
{wiki=Filter_(set_theory)}
A filter $\mathcal F$ on a set $X$ is a nonempty family of subsets that excludes the empty set, is closed under finite intersections, and is upward closed under inclusion.