Symbolic model checking represents the set of states and transition relation as Boolean func- tions, using Binary Decision Diagrams (BDDs). One alternative to common BDDs are Zero- suppressed Decision Diagrams (ZDDs), which are BDDs based on a new reduction rule. The efficiency of ZDD representation, in comparison with the original BDD, is noticeable especially for sparse state spaces, in which the actual number of existing states is much smaller than the total number of possible states.

To the best of our knowledge, the current implementation for ZDDs is using fixed set of vari- ables, i.e., domain for all possible diagrams. This may result in increase of size for each diagram. The main goal of this project is to develop an implementation of ZDDs with possibility of hav- ing different domains for specific diagrams. The secondary goal is to investigate the efficiency of ZDDs in comparison with BDDs, e.g. memory usage and running time, for reachability algorithm.