Before revision:  Our model is a microscopic one, similar to the interacting particle models of statistical physics . Events are considered random and modelled by a continuous time, finite state Markov process, that is, they are controlled by  independent exponential clocks.
After revision:  Our model is a microscopic one, similar to the interacting particle models of statistical physics . Events are considered random and modeled by a continuous time, finite state Markov process, that is, they are controlled by independent exponential clocks.