Bounded Width Branching Programs

Abstract

We examine the branching program model of computation and in particular the classes of languages which can be recognized when the width of the programs is bounded by a constant. After slightly revising the framework of definitions to sharpen analogies with other models, we prove that width 5 polynomial size branching programs can recognize exactly the parallel complexity class NC1, refuting a conjecture of Borodin et al. in [BDFP83].