Generalized P-Systems with Splicing and Cutting/Recombination RUDOLF FREUND Institut für Computersprachen, Technische Universität Wien, Karlsplatz 13, A-1040 Wien, Austria E-mail: rudi@logic.at; Tel.: ++43 1 58801 18542 Abstract. P-systems recently were introduced by Gheorghe P˘ aun as a new model for computa- tions based on membrane structures. Using the membranes as a kind of filter for specific objects when transferring them into an inner compartment turned out to be a very powerful mechanism in combination with suitable rules to be applied within the membranes in the model of generalized P- systems, GP-systems for short. In general, GP-systems allow for the simulation of graph controlled grammars of arbitrary type based on productions working on single objects. In this paper we consider GP-systems as computing devices using splicing or cutting and recombination of strings. Various variants of such systems are proved to have universal computational power, e.g., we show how test tube systems based on splicing or cutting and recombination of strings can be simulated by the corresponding GP-systems. Key words: P-systems, molecular computing, splicing 1. Introduction In the model of P-systems as introduced in P˘ aun (1999), the most important feature is the membrane structure (for a chemical variant of this idea see Berry and Boudol (1992)) consisting of membranes hierarchically embedded in the outermost skin membrane. Every membrane encloses a region possibly containing other mem- branes; the part delimited by the membrane labelled by k and its inner membranes is called compartment k. A region delimited by a membrane not only may en- close other membranes but also specific objects and operators, which in general are considered as multisets, as well as evolution rules, which in generalized P- systems (GP-systems) as introduced in Freund (1999) are evolution rules for the operators. In GP-systems, ground operators as well as transfer operators (simple rules of that kind are called travelling rules in Petre (1999)) are taken into account; these transfer operators transfer objects or operators (or even rules) either to the outer compartment or to an inner compartment delimited by a membrane of specific kind with also checking for some permitting and/or forbidding conditions on the objects to be transferred (in that way, the membranes act as a filter like in test tube systems, see P˘ aun, Rozenberg, and Salomaa (1998)). In contrast to the original definition of P-systems, in GP-systems no priority relations on the rules are used, because this feature can be captured in another way by using the transfer conditions in the transfer operators. Moreover, in general the objects are not affected in parallel Grammars 2: 189–199, 1999. © 1999 Kluwer Academic Publishers. Printed in the Netherlands.