Abstract
In a previous paper, we presented several extensions of ACP with
conditional expressions, including one with a retrospection operator on conditions to allow for looking back on conditions under which
preceding actions have been performed.
In this paper, we add a constant for a process that is only capable of
terminating successfully to those extensions of ACP, which can be very useful in applications.
It happens that in all cases the addition of this constant is
unproblematic.
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