Unit RR, Part B2: Vector Feedback

What is known:

• retrospective: everything (incl. relevance)
• predictive:
  • results from initial search
  • profile of interest and some relevant documents
  • statistics from previous sessions

Which retrieved documents are used:

• Rocchio: positive and negative
• Ide: dec hi

Feedback policies / heuristics

• Add terms from relevant retrieved that occur there more often than regular terms.
• Limit expansion to best terms.
• Re-weight based on relevant set.
• Combine old query and delta vectors to get new query.