Simulating the Fredkin Gate with Energy-Based P Systems

Reversibility plays a fundamental role when the possibility to perform computations with minimal energy dissipation is considered. Many papers on reversible computation have appeared in literature: the most famous are certainly the work of Bennett on (universal) reversible Turing machines and the work of Fredkin and Toffoli on conservative logic. The latter is based upon the Fredkin gate, a reversible and “conservative” (according to a definition given by Fredkin and Toffoli) three–input/three–output boolean gate. In this paper 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. Moreover, we show how energy–based P systems can be used to simulate the Fredkin gate. The proposed P systems that perform the simulation turn out to be themselves reversible and conservative.