Keyphrases
- lower bound
- upper bound
- query processing
- query language
- highly ranked
- efficient processing
- np hard
- query formulation
- branch and bound
- branch and bound algorithm
- objective function
- database queries
- user queries
- response time
- data sources
- retrieval systems
- web search engines
- worst case
- complex queries
- lower and upper bounds
- web queries
- lower bounding
- database
- query evaluation
- search queries
- relational databases