Technical Reports (CIS)

Document Type

Technical Report

Subject Area

CPS Formal Methods

Date of this Version

May 1998


University of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-98-12.


We propose ordered choice diagrams (OCD) for symbolic representation of boolean functions. An OCD is a nondeterministic variant of an ordered binary decision diagram (BDD) with appropriate reduction rules. The introduction of nondeterminism destroys canonicity, but affords significant succinctness. While OCDs have efficient algorithms for union, intersection, existential quantifier elimination, and emptiness test, the equivalence problems for OCDs is coNP-complete. We show that symbolic model checking can still be performed efficiently by replacing equivalence test with a stronger equality test. We report on a prototype implementation and preliminary results that indicate the advantage of OCD-based representation in reachability analysis of distributed protocols.



Date Posted: 01 November 2006