Keyphrases
- phrase structure
- natural language
- query language
- natural language processing
- visual languages
- query processing
- response time
- formal language
- query logs
- database queries
- context free
- tree structures
- database
- algebraic operators
- grammatical inference
- efficient processing
- web search engines
- data sources
- query formulation
- query evaluation
- range queries
- retrieval systems
- user queries
- penn treebank
- tree bank
- databases