A Compact Representation of Preference Queries

Preferences, which control our decisions in the daily life, have been widely studied and analyzed in computer science. In artificial intelligence, preferences are used in many domains such as decision theory, learning, etc. Several representations and reasoning techniques of preferences were proposed. One of these representations is the non-monotonic logic of preferences characterized by the ability to express several interpretations of preferences simultaneously. In relational databases, preferences are used for the personalization of queries to reduce the volume of data presented to the user by offering only the information that interests him. There, preferences are typically specified using binary preference relations among tuples. Binary preference relations are defined by preference formulas which can be embedded into classical relational queries. This paper is intended to discuss the encoding of relational database preference queries in the framework of the non-monotonic logic of preferences. We show that this framework allows the representation of binary preference relations that are asymmetric orders. In addition, it provides several mechanisms to manipulate preference queries efficiently.