Introduction to the 28th International Conference on Logic Programming Special Issue

We are proud to introduce this special issue of the Journal of Theory and Practice of Logic Programming (TPLP), dedicated to the full papers accepted for the 28th International Conference on Logic Programming (ICLP). The ICLP meetings started in Marseille in 1982 and since then constitute the main venue for presenting and discussing work in the area of logic programming

Preprocessing of Complex Non-Ground Rules in Answer Set Programming

In this paper we present a novel method for preprocessing complex non-ground rules in answer set programming (ASP). Using a well-known result from the area of conjunctive query evaluation, we apply hypertree decomposition to ASP rules in order to make the structure of rules more explicit to grounders. In particular, the decomposition of rules reduces the number of variables per rule, while on the other hand, additional predicates are required to link the decomposed rules together. As we show in this paper, this technique can reduce the size of the grounding significantly and thus improves the performance of ASP systems in certain cases. Using a prototype implementation and the benchmark suites of the Answer Set Programming Competition 2011, we perform extensive tests of our decomposition approach that clearly show the improvements in grounding time and size