Consistent query answers in inconsistent databases
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Elements Of Finite Model Theory (Texts in Theoretical Computer Science. An Eatcs Series)
Elements Of Finite Model Theory (Texts in Theoretical Computer Science. An Eatcs Series)
First-order query rewriting for inconsistent databases
Journal of Computer and System Sciences
On the consistent rewriting of conjunctive queries under primary key constraints
Information Systems
Minimal-change integrity maintenance using tuple deletions
Information and Computation
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
FQAS'11 Proceedings of the 9th international conference on Flexible Query Answering Systems
Certain conjunctive query answering in first-order logic
ACM Transactions on Database Systems (TODS)
On the data complexity of consistent query answering
Proceedings of the 15th International Conference on Database Theory
Certain conjunctive query answering in SQL
SUM'12 Proceedings of the 6th international conference on Scalable Uncertainty Management
Charting the tractability frontier of certain conjunctive query answering
Proceedings of the 32nd symposium on Principles of database systems
A dichotomy in the complexity of counting database repairs
Journal of Computer and System Sciences
Efficient querying of inconsistent databases with binary integer programming
Proceedings of the VLDB Endowment
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A natural way for capturing uncertainty in the relational data model is by allowing relations that violate their primary key. A repair of such relation is obtained by selecting a maximal number of tuples without ever selecting two tuples that agree on their primary key. Given a Boolean query q, CERTAINTY(q) is the problem that takes as input a relational database and asks whether q evaluates to true on every repair of that database. In recent years, CERTAINTY(q) has been studied primarily for conjunctive queries. Conditions have been determined under which CERTAINTY(q) is coNP-complete, first-order expressible, or not first-order expressible. A remaining open question was whether there exist conjunctive queries q without self-join such that CERTAINTY(q) is in PTIME but not first-order expressible. We answer this question affirmatively.