A Note on P Systems with Activators

Abstract

The usual assumption in P systems behavior is that of maximal parallelism, however in living cells it is not the case because they have a limited number of enzymes. The aim of this paper is to try to merge these ideas by introducing a notion of activator - a formal model of enzyme as a usual symbol- object, more or less a middle notion between a catalyst and a promoter. Each activator executes one (context-free) rule, and can evolve in the same step. The rules will need activators to be applied, so the parallelism of each rule is maximal, but limited to the number of its activators. Such systems can generate any recursively enumerable language or determinis- tically accept any recursively enumerable set of vectors of nonnegative integers. It is open what is the power of P systems with uniport rules and activators