Between Tree Patterns and Conjunctive Queries: Is There Tractability beyond Acyclicity?
Filip MurlakMichal OginskiMarcin PrzybylkoPublished in: MFCS (2012)
Keyphrases
- tree patterns
- conjunctive queries
- query answering
- np complete
- bounded treewidth
- data exchange
- queries using views
- xml queries
- query rewriting
- query containment
- data complexity
- exact learning
- semistructured data
- integrity constraints
- query evaluation
- structural features
- computational complexity
- schema mappings
- data integration
- np hard
- query language
- decision procedures
- probabilistic databases
- special case
- incomplete information
- data management
- null values
- dnf formulas
- data structure
- xml schema
- expressive power