I don't understand Hillel's point 1, since I assumed the proposed
translation would apply only when there is no code between label b and
label c1 or d1. His point 2 isn't compelling either, because the
difference between control in process p being at b or at c1 or at c2
is observable only by reading value of pc[p], and in multiprocess
algorithms, other processes are usually assumed not to be able to
access that value.
However, the proposal is unacceptable because it would provide a
quite unexpected translation if C1 or D1 were a while loop.
Leslie