  In this paper we introduce the idea of probability in the definition of
Sequential Dynamical Systems, thus obtaining a new concept, Probabilistic
Sequential System. The introduction of a probabilistic structure on Sequential
Dynamical Systems is an important and interesting problem.
  The notion of homomorphism of our new model, is a natural extension of
homomorphism of sequential dynamical systems introduced and developed by
Laubenbacher and Paregeis in several papers. Our model, give the possibility to
describe the dynamic of the systems using Markov chains and all the advantage
of stochastic theory. The notion of simulation is introduced using the concept
of homomorphisms, as usual. Several examples of homomorphisms, subsystems and
simulations are given.
