On conjunctive queries containing inequalities
Journal of the ACM (JACM)
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PODS '92 Proceedings of the eleventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
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PODS '94 Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
A technique for proving decidability of containment and equivalence of linear constraint queries
Journal of Computer and System Sciences
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Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
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VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
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Proceedings of the first international workshop on Interoperability of heterogeneous information systems
Containment of conjunctive queries with arithmetic expressions
OTM'05 Proceedings of the 2005 Confederated international conference on On the Move to Meaningful Internet Systems - Volume >Part I
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While the complexity of containment of standard conjunctive queries is NP-complete, adding constraints changes the complexity to $\Pi^P_2$-complete. This is because in such cases, we need to consider a team of containment mappings to establish containment as opposed to considering a single containment mapping in the standard case. The situation is different when homomorphism property holds, where considering a single mapping is sufficient to establish containment. We identify new classes of conjunctive queries with constraints that satisfy homomorphism property. For each class, we introduce a set of polynomial membership tests. Based on this, we propose an algorithm for rewriting of conjunctive queries with linear arithmetic constraints for which homomorphism property holds.