Semantics and Pragmatics of Preference Queries in Digital Libraries

As information becomes available in increasing amounts, and to growing numbers of users, the shift towards a more user-centered, or personalized access to information becomes crucial. In this paper we consider the semantics and pragmatics of preference queries over tables containing information objects described through a set of attributes. In particular, we address two basic issues: – how to define a preference query and its answer (semantics) – how to evaluate a preference query (pragmatics) With respect to existing work, our main contributions are (a) the proposal of an expressive language for declaring qualitative preferences, (b) a unified framework for expressing and evaluating both quantitative and qualitative preference queries and (c) rewriting algorithms for processing such queries. Although our main motivation originates in digital libraries, our proposal is quite general and can be used in several application contexts