NoMoRe: Non-monotonic Reasoning with Logic Programs

Abstract

The non-monotonic reasoning system noMoRe [2] implements answer set semantics for normal logic programs. It realizes a novel, rule-based paradigm to compute answer sets by computing non-standard graph colorings of the block graph associated with a given logic program (see [8],[9],[6] for details). These non-standard graph colorings are called a-colorings or application-colorings since they reflect the set of generating rules (applied rules) for an answer set. Hence noMoRe is rule-based and not atom-based like most of the other known systems. In the recent release of noMoRe we have added backward propagation of partial a-colorings and a technique called jumping in order to ensure full (backward) propagation [6]. Both techniques improve the search space pruning of noMoRe. Furthermore, we have extended the syntax by integrity, weight and cardinality constraints [11],[5]¹.

Observe, that we use a transformation for weight and cardinality constraints into normal logic programs, which is exponential in the worst case. That is, so far we did not consider efficiency issues when dealing with these constraints.