Let $S$ is a partition of a set $U$. Let $c$ is an ultrafilter on $U$.
Prove or disprove the followingthis conjecture:
At least one of the following is true:
- $\exists D\in S, C\in c:C\subseteq D$ or
- $\exists C\in c\forall D\in S: \mathrm{card}(C\cap D)\le 1$.