Implementation of Vector Space Model

1
Implementation of Vector Space Model

• March 27, 2006

2
How TA Can Be Used in Vector Space Model?

• Let consider a query with keyword microsoft and
  corporation,
• q (microsoft, corporation)
• Create table for each keyword, e.g.,
• These lists are called Inverted Lists

docid
Tfmicosoft Idfmicrosoft
docid
Tfcorporation Idfcorporation
374 289
43.2 42.1
175 456
23.5 20.1
- Space occupied O( of non-zero entries in the
matrix)
- So its not cheap in terms of space
3
How TA Can Be Used in Vector Space Model?

• Inverted List
• In original database words are generated for
  given documents
• In Inverted List, documents are generated for
  given words thats why this is called Inverted
  List

4
How TA Can Be Used in Vector Space Model?

• Inverted List
• Union of Listmicrosoft and Listcorporation
• Keep list sorted by document id
• Intersection of Listmicrosoft and Listcorporation
• Arrange keywords from more specific to the least