The Clowder Project

Sometimes one finds the notation

for $f_{*}$. This notation comes from the fact that the following statements are equivalent, where $b\in B$ and $U\in \mathcal{P}\webleft (A\webright )$:

• We have $b\in \forall _{f}\webleft (U\webright )$.
• For each $a\in A$, if $b=f\webleft (a\webright )$, then $a\in U$.