Journal of Computer and System Sciences
Database management systems
Circumscribing DATALOG: expressive power and complexity
Theoretical Computer Science
The OPL optimization programming language
The OPL optimization programming language
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Compiling Problem Specifications into SAT
ESOP '01 Proceedings of the 10th European Symposium on Programming Languages and Systems
Scheduling Aircraft Landings--The Static Case
Transportation Science
Existential second-order logic over graphs: charting the tractability frontier
FOCS '00 Proceedings of the 41st Annual Symposium on Foundations of Computer Science
Predicate-calculus-based logics for modeling and solving search problems
ACM Transactions on Computational Logic (TOCL)
Combining relational algebra, SQL, constraint modelling, and local search
Theory and Practice of Logic Programming
A framework for representing and solving NP search problems
AAAI'05 Proceedings of the 20th national conference on Artificial intelligence - Volume 1
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The goal of this paper is to provide a strong interaction between constraint programming and relational DBMSs. To this end we propose extensions of standard query languages such as relational algebra (RA) and SQL, by adding constraint solving capabilities to them. In particular, we propose non-deterministic extensions of both languages, which are specially suited for combinatorial problems. Nondeterminism is introduced by means of a guessing operator, which declares a set of relations to have an arbitrary extension. This new operator results in languages with higher expressive power, able to express all problems in the complexity class NP. Some syntactical restrictions which make data complexity polynomial are shown. The effectiveness of both languages is demonstrated by means of several examples.