Keyphrases
- database
- vector space
- query processing
- response time
- user queries
- keywords
- query expansion
- query evaluation
- database queries
- information retrieval
- complex queries
- search space
- data sources
- continuous functions
- query execution
- retrieval method
- data structure
- databases
- retrieval systems
- approximation algorithms
- lower bound
- feature space
- search engine
- query formulation