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3.4.4: Relevance Feedback (Rocchio)

To obtain weights for queries, global methods can be used. L ocal methods are not applicable because most queries are too short. In dialogue settings documents found with a query can be used to construct weights for a new query: users can be asked how useful these documents are.

The user is asked to give relevance judgements for the documents in a result set Dq={d1,...,dn} obtained with a query with the query vector q . This provides two subsets: R={d+1,...,d+r} , the set of documents judged relevant and U={d-1,...,d-u} , the set of documents judged not relevant. A new query vector is constructed based on the document vectors vd of a document d :

with real parameters , , and .


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© 1998 / HTML-Version 17. 11. 1998: R. Ferber