No abstract

No abstract

It is known that the satisfiability problem (SAT) can be solved a semiuniform family of deterministic polarizationless P systems with active membranes with non-elementary membrane division. We present a double improvement of this result by showing that the satisfiability of a quantified boolean formula (QSAT) can be solved by a uniform family of P systems of the same kind.

Abstract. This paper addresses the problem of removing the polarizations of membranes from P systems with active membranes -and this is achieved (sometimes, in restricted circumstances which we do not specify here) by allowing the change of membrane labels by means of communication rules (specifically, by rules sending objects out of membranes) or by membrane dividing rules. As consequences of these results, we obtain the universality of P systems with active membranes which are allowed to change the labels of membranes, but not using polarizations. Universality results are easily obtained also by direct proofs (this is achieved also for communication rules which bring objects into membranes). By direct constructions, we also prove that SAT can be solved in linear time by systems without polarizations and with label changing possibilities. Somewhat surprisingly, if non-elementary membranes can be divided, then SAT can be solved in linear time without using polarizations and label changing. Several open problems are also formulated.

No abstract

No abstract

a b s t r a c tA hybrid network of evolutionary processors (an HNEP) is a graph where each node is associated with an evolutionary processor (a special rewriting system), a set of words, an input filter and an output filter. Every evolutionary processor is given with a finite set of one type of point mutations (an insertion, a deletion or a substitution of a symbol) which can be applied to certain positions of a string over the domain of the set of these rewriting rules. The HNEP functions by rewriting the words that can be found at the nodes and then re-distributing the resulting strings according to a communication protocol based on a filtering mechanism. The filters are defined by certain variants of random-context conditions. HNEPs can be considered as both language generating devices (GHNEPs) and language accepting devices (AHNEPs). In this paper, by improving the previous results, we prove that any recursively enumerable language can be determined by a GHNEP and an AHNEP with 7 nodes. We also show that the families of GHNEPs and AHNEPs with 2 nodes are not computationally complete.

No abstract