Combinatorial optimization: algorithms and complexity
Combinatorial optimization: algorithms and complexity
Foundations of logic programming; (2nd extended ed.)
Foundations of logic programming; (2nd extended ed.)
Principles of database and knowledge-base systems, Vol. I
Principles of database and knowledge-base systems, Vol. I
Towards a theory of declarative knowledge
Foundations of deductive databases and logic programming
Journal of Computer and System Sciences
A catalog of complexity classes
Handbook of theoretical computer science (vol. A)
Journal of the ACM (JACM)
Theoretical Computer Science - Special issue on structure in complexity theory
A taxonomy of complexity classes of functions
Journal of Computer and System Sciences
Logical definability of NP optimization problems
Information and Computation
Approximation properties of NP minimization classes
Journal of Computer and System Sciences
Approximate solution of NP optimization problems
Theoretical Computer Science
The expressive powers of stable models for bound and unbound DATALOG queries
Journal of Computer and System Sciences - special issue on complexity theory
NP optimization problems in Datalog
ILPS '97 Proceedings of the 1997 international symposium on Logic programming
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Complexity and Approximation: Combinatorial Optimization Problems and Their Approximability Properties
Complements of multivalued functions
CCC '96 Proceedings of the 11th Annual IEEE Conference on Computational Complexity
Optimization of bound disjunctive queries with constraints
Theory and Practice of Logic Programming
Implementation and experimentation of the logic language NP Datalog
DEXA'06 Proceedings of the 17th international conference on Database and Expert Systems Applications
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It has been shown that NP (decision, search and optimization) problems can be expressed by means of DATALOG (Datalog with unstratified negation) queries under stable model semantics. Anyhow, the use of unrestricted negation is often neither simple nor intuitive and, besides, DATALOG does not allow to optimize queries and to discipline the expressive power. This paper analyzes the power of Datalog-like languages in expressing NP search and optimization problems. In more detail, in this paper we study the expressive power of several languages obtained by extending positive DATALOG with intuitive and efficient constructs, i.e. stratified negation, constraints and (exclusive) disjunction. Finally, we investigate a further restricted language, called NP Datalog, which uses disjunction only to define (nondeterministically) partitions of relations and which, in addition, captures the power of DATALOG in expressing search and optimization problems.