Extended faceted taxonomies for Web catalogs

Indexing and retrieval in Web catalogs can benefit from using faceted taxonomies. A faceted taxonomy consists of a set of facets, where each facet consists of a predefined set of terms structured by a subsumption relation. We propose two extensions of faceted taxonomies, which allow inferring conjunctions of terms that are valid in the underlying domain. We give a model-theoretic interpretation to these extended faceted taxonomies and we provide mechanisms for inferring the valid conjunctions of terms. This inference service can be exploited for preventing errors during the indexing process and for dynamically generating navigation trees that are suitable for browsing through the Web. The proposed scheme has several advantages by comparison to the hierarchical classification schemes that are currently employed by Web catalogs, namely: (a) conceptual clarity: it is easier to understand; (b) compactness: it takes less space; and (c) scalability: the update operations can be formulated easier and be performed more efficiently.