In the case where a mutex guards a data item the data item can be
implemented as a resolved signal in ParC. The resolution behavior can
be to only accept drive from one process at a time.
Barriers are normally used to synchronize a group of threads, in ParC a
fork can be used within a single process or a resolved signal can be
used between processes.
With the resolved signal approach the processes can drive (say) a 1 or
0 and the resolution function can be a straight sum. If each signal
reaching the barrier point drives 1 (and 0 otherwise) then it is faily
easy to tell when all threads are at the barrier (a count of drivers is
maintained forany resolved signal).