Combined-semantics equivalence of conjunctive queries: Decidability and tractability results.
Rada ChirkovaPublished in: J. Comput. Syst. Sci. (2016)
Keyphrases
- query containment
- conjunctive queries
- np complete
- query answering
- integrity constraints
- containment of conjunctive queries
- query evaluation
- decision procedures
- data complexity
- query language
- special case
- regular path queries
- query rewriting
- transitive closure
- datalog programs
- schema mappings
- regular expressions
- data exchange
- exptime complete
- incomplete information
- consistent query answering
- conp complete
- boolean expressions
- unions of conjunctive queries
- relational databases
- query optimization
- null values
- bounded treewidth
- probabilistic databases