Keyphrases
- query containment
- database query languages
- query language
- query processing
- database queries
- query evaluation
- query answers
- response time
- sparql queries
- aggregate functions
- conjunctive queries
- recursive queries
- relational calculus
- database systems
- nested relations
- decision procedures
- formal semantics
- efficient processing
- complex queries
- compositional semantics
- database
- query logs
- query terms
- conceptual model
- query optimization
- user queries
- logic programming
- open world
- null values
- consistent query answering
- relational algebra
- provenance information
- range queries
- retrieval systems
- web search engines
- information retrieval systems
- multi dimensional
- information retrieval