Using BDDs to Decide CTL

Computation Tree Logic (CTL) has been used quite extensively and successfully to reason about finite state systems. Algorithms have been developed for checking if a particular model satisfies a CTL formula (model checking) as well as for deciding if a CTL formula is valid or satisfiable. Initially, these algorithms explicitly constructed the model being checked or the model demonstrating satisfiability. A major breakthrough in CTL model checking occurred when researchers started representing the model implicitly via Boolean formulas. The use of ordered binary decision diagrams (OBDDs) as an efficient representation for these formulas led to a large jump in the size of the models that can be checked. This paper presents a way to encode the satisfiability algorithms for CTL in terms of Boolean formulas as well, so that symbolic model checking techniques using OBDDs can be exploited.