Model checking suffers from the state explosion problem, due to the exponential increase in the size of a finite state model as the number of system components grows. Directed model checking aims at reducing this problem through heuristic-based search strategies. The model of the system is built while checking the formula and this construction is guided by some heuristic function. In this line, we have defined a structure-based heuristic function operating on processes described in the Calculus of Communicating Systems (CCS), which accounts for the structure of the formula to be verified, expressed in the selective Hennessy-Milner logic. We have implemented a tool to evaluate the method and verified a sample of well known CCS processes with respect to some formulae, the results of which are reported and commented.
