Evaluation of Disjunctive Programs in WASP

Answer Set Programming (ASP) is a well-established declarative programming language based on logic. The success of ASP is mainly due to the availability of efficient ASP solvers, therefore their development is still an important research topic. In this paper we report the recent improvements of the well-known ASP solver wasp. The new version of wasp includes several improvements of the main solving strategies and advanced reasoning techniques for computing paracoherent answer sets. Indeed, wasp is the first ASP solver handling paracoherent reasoning under two mainstream semantics, namely semi-stable and semi-equilibrium. However, semi-equilibrium semantics may require the introduction of several disjunctive rules, which are usually considered as a source of inefficiency for modern solvers. Such a drawback is addressed in wasp by implementing ad-hoc techniques to efficiently handle disjunctive logic programs. These techniques are presented and evaluated in this paper.