Resource Discovery in Distributed Digital Libraries

In the near future, users will have access to a vast number of digital libraries. For a given information need and limited resources, there is the problem of selecting those libraries which produce an overall optimum answer. This resource discovery problem is additionally complicated by the diversity of the sources, e.g. with respect to media, document formats, indexing methods, database schemas and protocols. Once a set of digital libraries has been selected, the collection fusion problem deals with the problem of merging the answers of these libraries in order to get a high retrieval quality. This paper describes the specific problems and gives an overview on the solutions that have been developed so far.