Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
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
Queries Independent of Updates
VLDB '93 Proceedings of the 19th International Conference on Very Large Data Bases
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
On querying simple conceptual graphs with negation
Data & Knowledge Engineering
A Datatype Extension for Simple Conceptual Graphs and Conceptual Graphs Rules
ICCS '07 Proceedings of the 15th international conference on Conceptual Structures: Knowledge Architectures for Smart Applications
An Algorithmic Study of Deduction in Simple Conceptual Graphs with Classical Negation
ICCS '08 Proceedings of the 16th international conference on Conceptual Structures: Knowledge Visualization and Reasoning
A unified apriori-like algorithm for conjunctive query containment
IDEAS '08 Proceedings of the 2008 international symposium on Database engineering & applications
On Containment of Conjunctive Queries with Negation
ADBIS '09 Proceedings of the 13th East European Conference on Advances in Databases and Information Systems
Rethinking database updates using a multiple assignment-based approach
WSEAS Transactions on Computers
Containment of conjunctive queries with negation: algorithms and experiments
DEXA'10 Proceedings of the 21st international conference on Database and expert systems applications: Part II
DEXA'11 Proceedings of the 22nd international conference on Database and expert systems applications - Volume Part I
On the containment problem for queries in conjunctive form with negation
PSI'09 Proceedings of the 7th international Andrei Ershov Memorial conference on Perspectives of Systems Informatics
On the complexity of entailment in existential conjunctive first-order logic with atomic negation
Information and Computation
On the decidability and complexity of identity knowledge representation
DASFAA'12 Proceedings of the 17th international conference on Database Systems for Advanced Applications - Volume Part I
| Hi-index | 0.00 |
Query containment is a fundamental problem of databases. Given two queries q1 and q2, it asks whether the set of answers to q1 is included in the set of answers to q2 for any database. In this paper, we investigate this problem for conjunctive queries with negated subgoals. We use graph homomorphism as the core notion, which leads us to extend the results presented in [Ull97] and [WL03]. First, we exhibit sufficient (but not necessary) conditions for query containment based on special subgraphs of q2, which generalize that proposed in [WL03]. As a corollary, we obtain a case where the time complexity of the problem decreases. From a practical viewpoint, these properties can be exploited in algorithms, as shown in the paper. Second, we propose an algorithm based on the exploration of a space of graphs, which improves existing algorithms.