1. INFORMATION RETRIEVAL
-Monday March 21, 2006
-Arjun Dasgupta

2. IR DOMAINS Ranking functions in Traditional IR
Ranking functions used in the WWW
Ranking functions used in databases

3. RANKING FUNCTOINS IN TRADITIONAL IR
Started as a branch of library science
Definitions:
Corpus: a collection of documents
Document: a set/bag of words
Keyword Query: small set of keywords

4. An Example…. Query over the web = {Microsoft, Corporation}
An obvious approach would be to retrieve all documents containing “Microsoft” and “Corporation” ordered by the “ranking function”
Ranking function determines the order in which query results are presented

5. What constitutes a good ranking function???
Relative frequency of occurrence of keywords
Proximity of keywords (this cannot be done in a bag of words model)
Specificity or importance
Links to/from other documents
Popularity/ relevance of page with respect to the query