Binary decision diagrams by shared rewriting

Abstract

BDDs provide an established technique for propositional formula manipulation. In this paper we re-develope the basic BDD theory using standard rewriting techniques. Since a BDD is a DAG instead of a tree we need a notion of shared rewriting and develope appropriate theory. A rewriting system is presented by which canonical ROBDDs can be obtained. For this rewriting system a layerwise strategy is proposed having the same time complexity as the traditional algorithm, and a lazy strategy sometimes performing much better than the traditional algorithm.