18th RCRA international workshop on "experimental evaluation of algorithms for solving problems with combinatorial explosion"

The term Artificial Intelligence (AI) covers a wide set of techniques developed in very different areas, and although AI addresses very different types of problems, in many cases the efficiency of an AI program depends strongly on how it explores a search space. Most problems in AI have to explore a search space with a combinatorial explosion, and improvements developed in one area can propagate to other areas. RCRA (Rappresentazione della Conoscenza e Ragionamento Automatico, http://rcra.aixia.it) is the interest group on knowledge representation and automated reasoning of the Italian Association for Artificial Intelligence (AI*IA, http://www.aixia.it). The annual RCRA workshop has the aim to foster cross-fertilisation in different AI research areas, and welcomes contributions from all fields of AI and beyond.In the last years, the workshop addresses the experimental evaluation of algorithms in AI, having a combinatorially wide search space. In the 2011 edition (http://rcra.aixia.it/rcra2011), RCRA was held in Barcelona, Spain, as a workshop of the International Joint Conference on Artificial Intelligence (IJCAI 2011), one of the major conferences on AI. 26 papers were submitted to the workshop, and the Program Committee selected 20 of them for presentation, either as long presentations or as short presentations. Each paper was assigned three reviewers from the Program Committee. After the workshop, the authors had the opportunity to submit an extended version of their paper for possible publication. Each paper was reviewed again by three members of the program committee, not necessarily the same that had reviewed the paper for the workshop. After two rounds of reviews, the program committee selected the seven papers that compose this Special Issue.