Issue No. 09 - September (1996 vol. 45)

ISSN: 0018-9340

pp: 993-1002

DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/12.537122

ABSTRACT

<p><b>Abstract</b>—Ordered binary decision diagrams are a useful representation of Boolean functions, if a good variable ordering is known. Variable orderings are computed by heuristic algorithms and then improved with local search and simulated annealing algorithms. This approach is based on the conjecture that the following problem is NP-complete. Given an OBDD <it>G</it> representing <it>f</it> and a size bound <it>s</it>, does there exist an OBDD <it>G</it>* (respecting an arbitrary variable ordering) representing <it>f</it> with at most <it>s</it> nodes? This conjecture is proved.</p>

INDEX TERMS

Ordered binary decision diagrams, NP-completeness, variable orderings, verification, graph algorithms.

CITATION

Ingo Wegener, Beate Bollig, "Improving the Variable Ordering of OBDDs Is NP-Complete",

*IEEE Transactions on Computers*, vol. 45, no. , pp. 993-1002, September 1996, doi:10.1109/12.537122