Abstract.
We consider sequential variants of P-systems, the new model for computations using membrane structures and recently introduced by Gheorghe Paun. Using the permeabilty of the membranes for specific objects as a kind of filter turns out to be a very powerful mechanism in combination with suitable rules to be applied within the membranes. Generalized P-systems, GP-systems for short, constitute the most general model of sequential P-systems, considered in this paper. GP-systems allow for the simulation of graph-controlled grammars of arbitrary type based on productions working on single objects; for example, the general results we state in this paper can immediately be applied to the graph-controlled versions of context-free string grammars, n-dimensional # -context-free array grammars, and elementary graph grammars. Moreover, we consider GP-systems as molecular computing devices using splicing or cutting and recombination of strings. Various variants of such systems have universal computational power, too, e.g., test tube systems based on splicing or cutting and recombination of strings can be simulated by the corresponding GP-systems.