English
The infimum of a set S of filters is the supremum of their lower bounds: sInf(S) = sSup(lowerBounds S).
Русский
Наибольшая нижняя граница множества фильтров S равна супремуму их нижних границ: sInf(S) = sSup(lowerBounds S).
LaTeX
$$$\\operatorname{sInf}(S) = \\operatorname{sSup}(\\operatorname{lowerBounds} S)$$$
Lean4
/-- Infimum of a set of filters.
This definition is marked as irreducible
so that Lean doesn't try to unfold it when unifying expressions. -/
@[irreducible]
protected def sInf (s : Set (Filter α)) : Filter α :=
sSup (lowerBounds s)