\begin{frame}
  \frametitle{Conflicts}
  
  \begin{goal}{}
    Two actions in a schedule \emph{conflict} if they:
    \begin{itemize}
      \item are from \emph{different transactions},
      \item involve the \emph{same data item}, and
      \item \emph{one of the actions is a write}.
    \smallskip
    \end{itemize}
  \end{goal}

  \begin{exampleblock}{}
    \begin{tcenter}
      \begin{tikzpicture}
        \schedule{}{2}{1rY|1wY!1+3|2rY!1+3|2wZ|1wX}
      \end{tikzpicture}
    \end{tcenter}
  \end{exampleblock}
  \pause\pause\medskip

  \begin{goal}{}
    There are several types of \emph{conflicts}:
    \begin{itemize}
      \item \emph{write read} (WR)
      \item \emph{read write} (RW)
      \item \emph{write write} (WW)
    \smallskip
    \end{itemize}
  \end{goal}
  \pause\medskip
  
  \begin{alertblock}{}
    Such conflicts may cause a schedule to be not serializable.
  \end{alertblock}
\end{frame}