Integration of complex objects and transitive relationships for information retrieval

In this paper we show that in advanced information retrieval (IR) applications capabilities for data aggregation, transitive computation and NF2 (non-first normal form) relational computation are often necessary at the same time. We demonstrate that complex objects are naturally modeled as NF2 relations, whereas structures like hierarchical thesauri must be modeled for transitive computation. Transitive processing cannot be supported by structurally static structures like NF2 relations. We present a truly declarative query interface, which integrates data aggregation, transitive computation and NF2 relational computation. Thus the interface supports the retrieval and structural manipulation of complex objects (e.g. documents and bibliographic references), their retrieval through transitive relationships (e.g. thesauri, citations) and data aggregation based on their components (e.g. citation counts, author productivity). Most importantly, users can formulate queries on a high abstraction level without mastering actual programming or database techniques. (C) 1999 Elsevier Science Ltd. All rights reserved.