\documentclass{rtaloop}
\rtalabel{strong-confluence}


\begin{document}
\begin{problem}{Jean-Pierre Jouannaud}{}{April 1991}

\begin{abstract}
Which conditional rewrite systems are subcommutative?
\end{abstract}

Parallel rewriting with
orthogonal term-rewriting systems is ``subcommutative''
(a ``strong'' form of confluence).
Under which interesting syntactic restrictions do conditional
rewrite systems enjoy the same property?
It is known that orthogonal ``normal'' conditional rewriting systems 
(with conditions $u \rightarrow^! v$, where $v$ is a ground normal form) are
confluent, while ``standard'' (join) ones are not \cite{BK86:jcss}.

\end{problem}
\end{document}