Relaxing XML Preference Queries for Cooperative Retrieval

Today XML is an essential technology for knowledge management within enterprises and dissemination of data over the Web. Therefore the efficient evaluation of XML queries has been thoroughly researched. But given the ever growing amount of information available in different sources, also querying becomes more complex. In contrast to simple exact match retrieval, approximate matches become far more appropriate over collections of complex XML documents. Only recently approximate XML query processing has been proposed where structure and value are subject to necessary relaxations. All the possible query relaxations determined by the user’s preferences are generated in a way that predicates are progressively relaxed until a suitable set of best possible results is retrieved. In this paper we present a novel framework for developing preference relaxations to the query permitting additional flexibility in order to fulfil a user’s wishes. We also design IPX, an interface for XML preference query processing, that enables users to express and formulate complex user preferences, and provides a first solution for the aspects of XML preference query processing that allow preference querying and returning ranked answers.