Keyphrases
- transitive closure
- expressive power
- description logics
- deductive databases
- query answering
- np complete
- dl programs
- query language
- integrity constraints
- datalog programs
- logic programming
- data complexity
- refinement operators
- query evaluation
- first order logic
- relational algebra
- ontology based data access
- datalog queries
- directed acyclic graph
- ontology languages
- relational calculus
- stratified sampling
- fixpoint
- containment of conjunctive queries
- object oriented