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INFORMATION RETRIEVAL

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INFORMATION RETRIEVAL-Monday March 21, 2006-Arjun Dasgupta IR DOMAINS Ranking functions in Traditional IR Ranking functions used in the WWW Ranking functions used in ... – PowerPoint PPT presentation

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Title: INFORMATION RETRIEVAL


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
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