Sampling schemes for computing OBDD variable orderings

Abstract

We suggest some novel variable ordering techniques based upon the notion of sampling. Such techniques can produce highly effective static variable orders, and can thus be employed in numerous problems where current static variable ordering techniques prove totally inadequate. They can also augment various reordering techniques thereby helping to produce far superior variable orders in a comparable, or lesser, amount of time. Importantly, we have been able to build BDDs of circuits which could not be represented previously using numerous other reordering packages.