\begin{frame}
  \frametitle{Serializable Schedules}
  
  \begin{goal}{}
    A schedule is \emph{serial} if the actions of the different transactions are not interleaved;
    they are executed one after another.
  \end{goal}
  
  \begin{exampleblock}{}
    \begin{center}
      \begin{tikzpicture}
        \schedule{$S_1$}{2}{2rY|2wY|1rV|1wV}
      \end{tikzpicture}
    \end{center}
  \end{exampleblock}
  \pause
  \bigskip
  
  \begin{goal}{}
    A schedule is \emph{serializable} if its effect on the database 
    is the same as that of some serial schedule.
  \end{goal}
%   \remark{%
%     We assume that there are no effects other than the effects to the datbase,
%     i.e. no writing to the screen.
%   }
  \pause
  \bigskip
  
  \begin{quiz}{\textwidth}{Quiz Serializable Schedules}
    We usually only want to allow serializable schedules. Why?
  \end{quiz}
\end{frame}