\section{Concluding Discussions}

Our past work has been in three areas: modeling distributed
computations, predicate detection, and predicate control. We have
proposed to direct our future studies in these areas to target the
design of a prototype synchronization fault avoidance system. We think
that such a system is a ``good idea'' because of the following new
insights:  

\begin{itemize} 
\item Rollback and replay (or even weaker, rollback and restart) is
      an effective mechanism to avoid synchronization faults.  
\item Off-line synchronization is easier than on-line synchronization
      (to the extent that impossible problems become feasible).  
\item Identifying false causality leads to greater flexibility in
      the ordering of events which makes synchronization easier.
\end{itemize}
