Abstract: A method and system are provided of merging results in distributed information retrieval. A search manager (104) is in communication with a plurality of components, wherein a component is a search engine (106-108) working on a document collection and returning results in the form of a list of documents to a search query. The search manager (104) submits a query (202) to the plurality of components, receives results (213) from each component in the form of a list of documents; estimates (208) the success of a component in handling the query to generate a merit score (210) for a component per query; applies (220) the merit score (210) to the results for the component; and merges (222) results from the plurality of components by ranking in order of the applied merit score.

Abstract: A method and system for the detection of missing content in a searchable repository is provided. A system includes: a missing content query identifier (401) for identifying queries to a search engine (102) for which no or little relevant content is returned; a missing content detector (110) which clusters missing content queries by topic; and an output provider for providing details of a missing content topic.

Abstract: A query difficulty prediction unit includes a query difficulty predictor to determine the extent of overlap between query documents received from a search engine operating on an input query and sub-query documents received from the search engine operating on sub-queries of the input query. The unit generates a query difficulty prediction from the extent of overlap.