A Trichotomy in the Complexity of Counting Answers to Conjunctive Queries.
Hubie ChenStefan MengelPublished in: ICDT (2015)
Keyphrases
- conjunctive queries
- conjunctive query containment
- queries using views
- query evaluation
- data complexity
- integrity constraints
- query answering
- np complete
- combined complexity
- conp complete
- bounded treewidth
- query language
- conjunctive regular path queries
- probabilistic databases
- query rewriting
- pspace complete
- containment of conjunctive queries
- data exchange
- complexity of query answering
- query containment
- lower complexity
- decision procedures
- query answers
- computational complexity
- fixed parameter tractable
- boolean expressions
- datalog programs
- satisfiability problem
- deductive databases
- expressive power
- special case
- dl lite
- unions of conjunctive queries
- transitive closure
- schema mappings
- answering queries using views
- relational databases