Rudolf Freund

Graph-Controlled Insertion-Deletion Systems

In this article, we consider the operations of insertion and deletion working in a graph-controlled manner. We show that like in the case of context-free productions, the computational power is strictly increased when using a control graph: computational completeness can be obtained by systems with insertion or deletion rules involving at most two symbols in a contextual or in a context-free manner and with the control graph having only four nodes.

ω -P Automata with Communication Rules

We introduce ω -P automata based on the model of P systems with membrane channels (see [8]) using only communication rules. We show that ω -P automata with only two membranes can simulate the computational power of usual (non-deterministic) ω -Turing machines. A very restricted variant of ω -P automata allows for the simulation of ω -finite automata in only one membrane.

P Systems with Cutting/Recombination Rules Assigned to Membranes

We introduce a new variant of splicing P systems, where the rules are directly assigned to the membranes and not to the regions as this is usually observed in the area of membrane systems. The strings involved in the splicing operation are either taken from inside or from outside the membrane and the strings resulting from the splicing operation also may go inside or outside the membrane. Instead of the splicing operation, also the operations of cutting and recombination are used as rules assigned to membranes. For the application of rules leading from one configuration of the system to the succeeding configuration we consider a sequential model and do not use the model of maximal parallelism. We will show that for such sequential P systems using splicing rules or cutting/recombination rules assigned to the skin membrane we already obtain universal computational power with only one membrane.

Chocolate P Automata

We introduce several variants of input-driven tissue P automata – we also will call them chocolate automata – where the rules to be applied only depend on the input symbol. Both strings and multisets are considered as input objects; the strings are either read from an input tape or defined by the sequence of symbols taken in, and the multisets are given in an input cell at the beginning of a computation, enclosed in a vesicle. Additional symbols generated during a computation are stored in this vesicle, too. An input is accepted when the vesicle reaches a final cell and it is empty. The computational power of some variants of input-driven tissue P automata (chocolate automata) is illustrated by examples and compared with the power of the input-driven variants of other automata as register machines and counter automata.