The progress in information technology including artificial intelligence (AI) in the last few decades is remarkable, and has attracted many young researchers to this field. This trend is now accelerated along with the recent rapid growth of computer communication networks and the worldwide increase in researchers. In this context, we have observed many outstanding AI studies in Japanese dom- tic conferences. They have high technical originality, quality and significance. The annual conference of JSAI (Japan Society for Artificial Intelligence) is one of the key and representative domestic meetings in the field of intelligent inf- mation technology. Award papers in this conference have an excellent quality of international standards. The annual conference of JSAI also organizes co-located international workshops to provide excellent study reports. The objectives of this book are to present the award papers of the 20th annual conference of JSAI 2006 and selected papers from the three co-located international workshops and to promote the study exchange among researchers worldwide. Eight papers were awarded among more than 200 presentations in the conference, and 21 papers were selected from a total of 44 presentations in the workshops of Logic and Engineering of Natural Language Semantics 2006 (LENLS 2006), Learning with Logics and Logics for Learning (LLLL 2006) and Risk Mining (RM 2006). The award papers in the 20th annual conference of JSAI 2006 were selected from presentations covering the wide field of art- cial intelligence through the processes of candidate recommendations, detailed open discussions and voting by ProgramCommittee members of the conference.