“…The basis of such models is state machines, which can be used to model numerous variables and relate different system states (configurations) to one another [21]. There have been various attempts to model biological systems from a computational point of view, including the use of Boolean networks [31], Petri nets [45], the π-calculus [39], interacting state machines [25], L-systems [38] and variants of P systems (membrane systems) [5,17,23,29,33,42]. These techniques are useful for investigating the qualitative features, as are their stochastic counterparts (e.g., stochastic Petri Nets [26] and stochastic P systems [8,43]) are useful for investigating the quantitative features of computation models.…”