Simple random logic programs

Abstract

We consider random logic programs with two-literal rules and study their properties. In particular, we obtain results on the probability that random "sparse" and "dense" programs with two-literal rules have answer sets. We study experimentally how hard it is to compute answer sets of such programs. For programs that are constraint-free and purely negative we show that the easy-hard-easy pattern emerges. We provide arguments to explain that behavior. We also show that the hardness of programs from the hard region grows quickly with the number of atoms. Our results point to the importance of purely negative constraint-free programs for the development of ASP solvers. © 2009 Springer Berlin Heidelberg.