P systems are a biologically inspired model introduced by Gheorghe P¸aun
with the aim of representing the structure and the functioning of the cell. Since their
introduction, several variants of P systems have been proposed and explored.
We concentrate on the class of catalytic P systems without priorities associated to
the rules. We show that the divergence problem (i.e., checking for the existence of an
infinite computation) is decidable in such a class of P systems.
As a corollary, we obtain an alternative proof of the nonuniversality of deterministic
catalytic P systems, an open problem recently solved by Ibarra and Yen
