\begin{frame} \frametitle{Relationship Sets} \movieexample \bigskip \begin{block}{} A \emph{relationship \alert{set}} is a set of relationships of the same kind. \end{block} That is, a \emph{relationship set} is a set of tuples $(e_1,e_2,\ldots,e_n)$ where $e_1 \in E_1$, \ldots, $e_n \in E_n$ are from entity sets $E_1,\ldots,E_n$. \medskip \alt<-1>{ \begin{exampleblock}{} Example of a relationship set {\small \begin{talign} \{ \; &(\text{Uma Thurman},\,\text{Pulp Fiction}), \\ &(\text{Mark Hamill},\,\text{Star Wars}), \\ &(\text{Harrison Ford},\,\text{Star Wars}), \\ &(\text{Harrison Ford},\,\text{Indiana Jones}) \;\} \end{talign}\vspace{-2.3ex}} \end{exampleblock} }{ \begin{goal}{} The relationship set \textit{plays-in} between entity sets \textit{actor} and \textit{movie} is indicated as follows in ER models: \begin{center} \scalebox{.85}{ \begin{tikzpicture}[every edge/.style={link}] \node[entity] (actor) {actor}; \node[entity,right of=actor, node distance=6cm] (movie) {movie}; \node[relationship] (plays) at ($(actor)!.5!(movie)$) {plays-in} edge (actor) edge (movie); \end{tikzpicture}} \end{center} \end{goal} } \pause \vspace{10cm} \end{frame}