\frametitle{Serializable Schedules}
    A schedule is \emph{serial} if the actions of the different transactions are not interleaved;
    they are executed one after another.
    A schedule is \emph{serializable} if its effect on the database 
    is the same as that of some serial schedule.
    We assume that there are no effects other than the effects to the datbase,
    i.e. no writing to the screen.
  \begin{quiz}{\textwidth}{Quiz Serializable Schedules}
    We usually only want to allow serializable schedules. Why?