Keyphrases
- open problems
- information retrieval
- database theory
- computational advertising
- long standing
- search engine
- information retrieval systems
- information extraction
- multidatabase transaction management
- vector space model
- query expansion
- test collection
- learning to rank
- information access
- text mining
- knowledge discovery
- text retrieval
- question answering
- document collections
- retrieval systems
- document retrieval
- retrieval model
- database