Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Information Integration Using Logical Views
ICDT '97 Proceedings of the 6th International Conference on Database Theory
Containment of Conjunctive Queries with Safe Negation
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Answering queries using views: A survey
The VLDB Journal — The International Journal 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
Handbook of Constraint Programming (Foundations of Artificial Intelligence)
Handbook of Constraint Programming (Foundations of Artificial Intelligence)
On querying simple conceptual graphs with negation
Data & Knowledge Engineering
Containment of conjunctive queries over databases with null values
ICDT'07 Proceedings of the 11th international conference on Database Theory
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We consider the deduction problem in the existential conjunctive fragment of first-order logic with atomic negation. This problem can be recast in terms of other database and artificial intelligence problems, namely query containment, clause entailment and boolean query answering. We refine an algorithm scheme that was proposed for query containment, which itself improves other known algorithms in databases. To study it experimentally, we build a random generator and analyze the influence of several parameters on the problem instance difficulty. Using this methodology, we experimentally compare several heuristics.