1. Modern Information Retrieval Chapter 5 Query Operations

2. Original query  results  relevance judgment  query reformulation  better results Query reformulation Expanding the original query with new terms Re-weighting the terms in the expanded query

3. Three approaches Based on feedback information from the user Based on information derived from the local set of documents Based on information derived from the document collection User relevance feedback Selecting important terms from the relevant documents Enhancing the importance of these terms

4. For the vector model The term-weight vectors of the relevant documents are similar among themselves while dissimilar with non-relevant documents Reformulate the query such that it gets closer to the term-weight vector space of the relevant documents

5. D r : set of relevant documents retrieved D n : set of non-relevant documents retrieved C r : set of all relevant documents

6. when r =0  positive feedback strategy

7. Simple with good results Evaluate retrieval performance considering only the residual collection  feedback documents are removed