A Framework for Qualitative Multi-Criteria Preferences (extended abstract)

Introduction A key challenge in the representation of qualitative, multi-criteria preferences is to find a compact and expressive representation. Various frameworks have been introduced, each of which with its own distinguishing features. In this paper we introduce a new representation framework called qualitative preference systems (QPS), which combines priority, cardinality and conditional preferences. Moreover, the framework incorporates knowledge that serves two purposes: to impose (hard) constraints, but also to define new (abstract) concepts. QPSs are based on the lexicographic rule studied in [1]. This rule is a fundamental part of the framework presented as it offers a principled tool for combining basic preferences. We believe this ability to combine preferences is essential for any practical approach to representing qualitative preferences. It is needed in particular for constructing multi-criteria preferences. It is not sufficient, however, since more expressivity is needed and useful in practice. Therefore, QPSs in addition provide a tool for representing knowledge, for abstraction, for counting, and provide a layered structure for representing preference orderings. QPSs are able to represent various strategies for defining preference orderings, and are able to handle conditional preferences. Logical Preference Description language (LPD; [3]) can be embedded into the QPS framework and that there is an order preserving embedding of CP-nets [2] in the QPS framework. These embeddings provide a representation that is just as succinct as the LPD expressions and CP-nets.