Affiliations: Faculty of Mathematics and Computer Science, Nicolaus
Copernicus University, Toruń, Poland. khama@mat.uni.torun.pl | Faculty of Mathematics and Computer Science, Nicolaus
Copernicus University, Toruń, Poland and Institute of Computer
Science, Polish Academy of Sciences, Warszawa, Poland.
edoch@mat.uni.torun.pl
Note: [] Address for correspondence: Nicolaus Copernicus University,
Chopina 12/18, 87-100 Toruń, Poland
Abstract: The notion of persistency, based on the rule "no
action can disable another one" is one of the classical notions
in concurrency theory. We propose two ways of generalization of this notion:
the first is "no action can kill another one" and
the second "no action can kill another enabled
one". We study the three notions in the context of
place/transition nets, the fundamental class of Petri nets. We prove that the
three classes of persistency form an increased strict hierarchy. The final
section of the paper deals with decision problems about persistency. We show
that the set reachability problem is decidable for rational convex sets, and
using this result we prove that all kinds of persistency are decidable in the
class place/transition nets.
