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” docidTf micosoft * Idf microsoft 374 289 43.2 42.1 docidTf corporation * Idf corporation 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; that’s why this is called Inverted List

4. How TA Can Be Used in Vector Space Model? Inverted List  Union of List microsoft and List corporation Keep list sorted by document id  Intersection of List microsoft and List corporation Arrange keywords from more specific to the least