PP is as hard as the polynomial-time hierarchy
SIAM Journal on Computing
Consistent query answers in inconsistent databases
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Scalar aggregation in inconsistent databases
Theoretical Computer Science - Database theory
First-order query rewriting for inconsistent databases
Journal of Computer and System Sciences
Management of probabilistic data: foundations and challenges
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Approximate Probabilistic Query Answering over Inconsistent Databases
ER '08 Proceedings of the 27th International Conference on Conceptual Modeling
Probabilistic databases: diamonds in the dirt
Communications of the ACM - Barbara Liskov: ACM's A.M. Turing Award Winner
On the consistent rewriting of conjunctive queries under primary key constraints
Information Systems
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
A remark on the complexity of consistent conjunctive query answering under primary key violations
Information Processing Letters
Queries and materialized views on probabilistic databases
Journal of Computer and System Sciences
Proceedings of the 4th International Workshop on Logic in Databases
On the tractability and intractability of consistent conjunctive query answering
Proceedings of the 2011 Joint EDBT/ICDT Ph.D. Workshop
Determining the currency of data
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Hi-index | 0.00 |
Uncertainty is modeled by a multibase (db,μ) where db is a database with zero or more primary key violations, and μ associates a multiplicity (a positive integer) to each fact of db. In data integration, the multiplicity of a fact g can indicate the number of data sources in which g was found. In planning databases, facts with the same primary key value are alternatives for each other, and the multiplicity of a fact g can denote the number of people in favor of g. A repair of db is obtained by selecting a maximal number of facts without ever selecting two distinct facts of the same relation that agree on their primary key. Every repair has a support count, which is the product of the multiplicities of its facts. For a fixed Boolean query q, we define σCERTAINTY(q) as the following counting problem: Given a multibase (db,μ), determine the weighted number of repairs of db that satisfy q. Here, every repair is weighted by its support count. We illustrate the practical significance of this problem by means of examples. For conjunctive queries q without self-join, we provide a syntactic characterization of the class of queries q such that σCERTAINTY(q) is in P; for queries not in this class, σCERTAINTY(q) is $\sharp$ P-hard (and hence highly intractable).