implementing Dijkstra's guarded commands

[ark at alice.UUCP]

In article <515 at muffin.cme-durer.ARPA>, libes at cme-durer.UUCP writes:
> I am rendering an algorithm into C that was originally written using
> Dijkstra's guarded commands.  I am wondering if there is a nice way of
> writing the C so that the algorithm preserves the possibility for
> parallel execution

Dijkstra's guarded commands don't really allow for parallel
execution.  If you say

	if C1 -> S1
	 | C2 -> S2
	 | C3 -> S3
	fi

then exactly one of S1, S2, and S3 will be executed (or the
program will abort).  Where's the parallelism?