Universality results for some variants of P systems

P systems, introduced by Gh. Pǎaun, form a new class of distributed computing models. Many variants of P systems were shown to be computationally universal. In this paper, we consider several classes of P systems with symbol-objects where we allow the catalysts to move in and out of a membrane. We prove universality results for these variants of P systems with a very small number of membranes. © 2001 Springer-Verlag Berlin Heidelberg.