This volume draws mostly on papers presented at the TRENTO 2009 international workshop on Preferences and Decisions, jointly organized by the University of Trento and the University of Sannio at Benevento (Italy). Since its first edition in 1997, the renowned international workshop series TRENTO aims at providing an informal but effective opportunity for sharing and discussing the recent research developments in the field of preference modeling and decision theory, bringing together some of the world's leading experts in this active interdisciplinary area of research. In particular, the scope of the international workshop TRENTO 2009 covered a wide range of topics, such as preference representation and rationality, machine intelligence and automation in decision making, uncertainty modeling, probabilistic and possibilistic decision models, cooperative game theory and coalition formation, aggregation functions and multicriteria decision making, fuzzy set theory and fuzzy logic for decision making, algebraic structures, quantum dynamics, complex network models and negotiation, interactive dynamics and consensus reaching in multiagent decisions, optimization and operational research for decision making. The contributes have been proposed by authors that are among the most recognized scientists in the respective research domains. This volume also provides an opportunity, to colleagues and friends of Mario Fedrizzi, Benedetto Matarazzo, and Aldo Ventre, for celebrating and thanking them for their continuing and stimulating scientific work.

Decision making is an omnipresent, most crucial activity of the human being, and also of virtually all artificial broadly perceived "intelligent" systems that try to mimic human behavior, reasoning and choice processes. It is quite obvious that such a relevance of decision making had triggered vast research effort on its very essence, and attempts to develop tools and techniques which would make it possible to somehow mimic human decision making related acts, even to automate decision making processes that had been so far reserved for the human beings. The roots of those attempts at a scientific analysis can be traced to the ancient times but - clearly - they have gained momentum in the recent 50 or 100 years following a general boom in science. Depending on the field of science, decision making can be viewed in different ways. The most general view can be that decision making boils down to some cognitive, mental process(es) that lead to the selection of an option or a course of action among several alternatives. Then, looking in a deeper way, from a psychological perspective this process proceeds in the context of a set of needs, preferences, rational choice of an individual, a group of individuals, or even an organization. From a cognitive perspective, the decision making process proceeds in the context of various interactions with the environment.