%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%% %15 %%%%%%%%%%%%%%%%%%%%%%%%% \chapter[Equivalence relations and partitions.]{Prove the following correspondence between equivalence relations and partitions.} Let $A$ be a set. \begin{enumerate} \item Prove that if $R$ is an equivalence relation on $A$, then $\{[a] : a \in A\}$ is a partition of $A$. \item Prove that if $P$ is a partition of $A$, then $R = \{(x,y) : x,y \in X \text{ and } X \in P\}$ is an equivalence relation on $A$. \end{enumerate} \section{First draft} Due Wednesday, April 20 at 6:00 PM. \begin{proof} \end{proof}