Proton pumping P systems

We propose here a (biologically inspired) model of P system called proton pumping P system that is a special case of evolution-communication P system. In cell biology there are transport mechanisms, involving protons. We generalize this idea by considering a few different types of protons. A proton pumping P system is, essentially, an evolution-communication P system where a special subset of symbol-objects (called protons) is used. In such a system we have simple evolution rules (classical evolution rules without target indications), symport and antiport rules that exchange some objects (among them, possibly, other protons) for a proton; taking inspiration from biology, this particular type of antiports is often called proton pumping rules. We show that, as expected, the new model is universal, using non-cooperative rules, symport and antiport rules of weight one, and enough types of protons available for the computation. If we decrease the number of types of protons to one or two, then the model is at least as powerful as ETOL system, provided that (total) weak or strong priority of antiport rules over symport and evolution rules are used. Finally, we consider some descriptional complexity measures (again, inspired from biology) for the newly introduced model. © Springer-Verlag Berlin Heidelberg 2004.