Eilenberg P Systems with Symbol-Objects
A class of P systems, called EOP systems, with symbol objects processed by evolution rules distributed alongside the transitions of an Eilenberg machine, is introduced. A parallel variant of EOP systems, called EOPP systems, is also defined and the power of both EOP and EOPP systems is investigated in relationship with three parameters: number of membranes, states and set of distributed rules. It is proven that the family of Parikh sets of vectors of numbers generated by EOP systems with one membrane, one state and one single set of rules coincides with the family of Parikh sets of context-free languages. The hierarchy collapses when at least one membrane, two states and four sets of rules are used and in this case a characterization of the family of Parikh sets of vectors associated with ET0L languages is obtained. It is also shown that every EOP system may be simulated by an EOPP system and EOPP systems may be used for solving NP-complete problems. In particular linear time solutions are provided for the SAT problem.
KeywordsConjunctive Normal Form Priority Relationship Evolution Rule Terminal Symbol Membrane Computing
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