20th RCRA International workshop on “Experimental evaluation of algorithms for solving problems with combinatorial explosion”

Problems arising in several areas of computer science have combinatorial nature. Solving these problems with reasonable performance is often both a challenging and crucial task, because feasible or optimal decisions often depend on a non-trivial combination of various factors. Nonetheless, algorithms developed in one research area are often applicable to similar problems, or can be hybridised with techniques developed in other areas to improve the performance of existing solutions. Cross-fertilising areas, so to merge the viewpoints of different communities that try to solve similar problems, can result in faster development of effective solutions. This is one of the aims of the RCRA (Ragionamento Automatico e Rappresentazione della Conoscenza) group, the interest group of the Italian Association for Artificial Intelligence (AI*IA) on knowledge representation and automated reasoning, which organises its annual meetings since 1994. Scope of the workshop is fostering the cross-fertilisation of ideas stemming from different areas, proposing benchmarks for new challenging problems, comparing models and algorithms from an experimental viewpoint and, in general, comparing different approaches with respect to efficiency, problem modelling and ease of development. Since the 2005 edition, the RCRA workshops have focussed on the theme of algorithms in Artificial Intelligence (AI). These meetings have reached the objective to put together researchers coming from AI fields as diverse as constraint satisfaction, machine learning, logic languages, quantified satisfiability, planning and scheduling, just to name a few. The event has gained more and more interest, first from the Italian community, then from the international one. In 2008, the workshop was co-located with the International Conference on Logic Programming (ICLP 2008), in 2010 the event was in association with the seventh International Conference on Integration of Artificial Intelligence and Operations Research techniques in Constraint Programming (CP-AI-OR 2010), whereas in 2011 it was a satellite workshop of the TwentySecond International Joint Conference on Artificial Intelligence (IJCAI 2011). The 2012 edition of the RCRA workshop was held in Rome, on 14–15 June 2012 in association with the 12th AI*IA Symposium on Artificial Intelligence (AI*IA 2012). The success of these events shows that RCRA is becoming a major forum for exchanging ideas and proposing experimentation methodologies for algorithms in AI. The 2013 edition of the RCRA workshop was held in Rome, on 14–15 June 2013. At the workshop, 14 papers were presented, and the authors had the possibility to submit an extended version of their paper for possible publication in this special issue. After several rounds of reviews, the following six papers were selected. Campeotto et al. provides a novel perspective in the protein structure prediction (PSP) problem. Dvorak et al. investigate various methods for automated generation of efficient state-variable representations from the propositional representation of Planning problems, performing an exhaustive experimental evaluation of methods, planning