- Since user already seen results above, and they haven’t clicked and continue reading
- What next the results should be?
- Increase diversity to satisfy all users for reduction of global relevance
Diverse Results Example
- word apple can mean a company or a fruit
- web search should cover both of these meanings (aspects)
Query Reformulations for Web Search Diversification
How to Query Reformulations Work?
- How relevant the document to the user, given already seen higher results?
- Each document added to results should cover different aspect
- Previous methods: similarity between docs using maximal marginal relevance
- Paper contribution: similarity between sub-queries
- query reformulations provided by three major Web search engines
- Created probably via query log mining
- related sub-queries + suggested sub-queries
- relative importance generated sub-queries from centralized ranking of documents covering them
Coverage and Submodularity
Coverage is a submodularity and diminishing returns problem - read more here