On a class of P automata

In this paper, we propose a class of P automata in which each membrane has a state, like in tissue P systems [5], and the computation starts at some initial state and ends in a final state. Unlike the automaton considered in [2], where rules are used in sequential manner, here we consider a variant such that the rules can be applied in maximal mode (as defined in tissue P systems). We show that P automata characterize the recursively enumerable sets of vectors of natural numbers.