We introduce the first substantial approach to preprocessing in the context of answer set solving. The idea is to simplify a logic program while identifying equivalences among its relevant constituents. These equivalences are then used for building a compact representation of the program (in terms of Boolean constraints). We implemented our approach as well as a SAT-based technique to reduce Boolean constraints. This allows us to empirically analyze both preprocessing types and to demonstrate their computational impact.

This paper gives a summary of the First Answer Set Programming System Competition that was held in conjunction with the Ninth International Conference on Logic Programming and Nonmonotonic Reasoning. The aims of the competition were twofold: first, to collect challenging benchmark problems, and second, to provide a platform to assess a broad variety of Answer Set Programming systems. The competition was inspired by similar events in neighboring fields, where regular benchmarking has been a major factor behind improvements in the developed systems and their ability to address practical applications.

We elaborate upon a recently proposed approach to finding an answer set of a logic program based on concepts from constraint processing and satisfiability checking. We extend this approach and propose a new algorithm for enumerating answer sets. The algorithm, which to our knowledge is novel even in the context of satisfiability checking, is implemented in the clasp answer set solver. We contrast our new approach to alternative systems and different options of clasp, and provide an empirical evaluation.

We introduce a new approach to computing answer sets of logic programs, based on concepts from constraint processing (CSP) and satisfiability checking (SAT). The idea is to view inferences in answer set programming (ASP) as unit propagation on no-goods. This provides us with a uniform constraint-based framework for the different kinds of inferences in ASP. It also allows us to apply advanced techniques from the areas of CSP and SAT. We have implemented our approach in the new ASP solver clasp. Our experiments show that the approach is competitive with state-of-the-art ASP solvers.

We describe the conflict-driven answer set solver clasp, which is based on concepts from constraint processing (CSP) and satisfiability checking (SAT). We detail its system architecture and major features, and provide a systematic empirical evaluation of its features.

We present a new answer set solver nomore++. Distinguishing features include its treatment of heads and bodies equitably as computational objects and a new hybrid lookahead. nomore++ is close to being competitive with stateof-the-art answer set solvers, as demonstrated by selected experimental results.

We present a new answer set solver, called nomore++, along with its underlying theoretical foundations. A distinguishing feature is that it treats heads and bodies equitably as computational objects. Apart from its operational foundations, we show how it improves on previous work through its new lookahead and its computational strategy of maintaining unfounded-freeness. We underpin our claims by selected experimental results.

This document presents the results of an elaborate human factors study on multimodal interaction in bathroom design Author: Louis Vuurpijl, Louis ten Bosch, Stéphane Rossignol, Andre Neumann, Ralf Engel, Norbert Pfleger Reviewers: Els den Os, Lou Boves, Michael White