Pumps Systems of Membranes

The reactivity of the living cells provides the real complexity of biological systems. This paper presents a reactive P system where the rules are triggered by certain conditions, and pumps are the parallel processors of a membrane. The computation of a reactive P system is given by parallel composition of conditional rules regarding the pumps, and by sequential and parallel composition of internal rules regarding the coordination activity of the membrane nucleus. Starting from this description, it is possible to de¯ne the operational semantics and various behavioural equivalences between mem- branes. Finally, some perspectives and open problems are presented. Overall this approach is a step toward a programming paradigm inspired by membrane activity.