Reversible P systems to simulate Fredkin circuits

We introduce energy-based P systems as a parallel and distributed model of computation in which the amount of energy manipulated and/or consumed during computations is taken into account. Basin-upon the seminal paper of Fredkin and Toffoli on conservative logic, we first show how energy-based P systems can be used to simulate the Fredkin gate, a reversible and conservative three-input/three-output boolean gate which is functionally complete for boolean logic. Then, we show how any reversible Fredkin circuit can be simulated by energy-based P systems whose number of membranes is independent of the number of gates occurring in the simulated circuit. The simulating P systems turn out to be themselves reversible and conservative.