Tissue P Systems with Point Mutation Rules

We consider tissue P systems working in the sequential mode on vesicles of multisets with the very simple operations of insertion, deletion, and substitution of single objects. In a computation step, one rule is to be applied if possible, and then, in any case, the whole multiset being enclosed in a vesicle moves to one of the cells as indicated by the underlying graph structure of the system. The target cell is chosen in a non-deterministic way and does not depend on the possibly applied rule. With defining halting as reaching the final cell with a vesicle only containing terminal symbols, computational completeness can be obtained. Imposing the restriction that in each derivation step one rule has to be applied, we only reach the computational power of matrix grammars for multisets. Moreover, we also discuss variants for computations on strings. Finally, we outline a way how to “go beyond Turing” like with red-green register machines.