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Foundations of Databases: The Logical Level
Computers and Intractability: A Guide to the Theory of NP-Completeness
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Condensed Representation of Database Repairs for Consistent Query Answering
ICDT '03 Proceedings of the 9th International Conference on Database Theory
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Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Scalar aggregation in inconsistent databases
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A cost-based model and effective heuristic for repairing constraints by value modification
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Minimal-change integrity maintenance using tuple deletions
Information and Computation
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Constraint Databases
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Consistent query answers on numerical databases under aggregate constraints
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DART: a data acquisition and repairing tool
EDBT'06 Proceedings of the 2006 international conference on Current Trends in Database Technology
Consistent Query Answering: The First Ten Years
SUM '08 Proceedings of the 2nd international conference on Scalable Uncertainty Management
On approximating optimum repairs for functional dependency violations
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Incorporating cardinality constraints and synonym rules into conditional functional dependencies
Information Processing Letters
Analyses and Validation of Conditional Dependencies with Built-in Predicates
DEXA '09 Proceedings of the 20th International Conference on Database and Expert Systems Applications
Querying and repairing inconsistent numerical databases
ACM Transactions on Database Systems (TODS)
Disjunctive databases for representing repairs
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Preserving consistency and security of data in e-business applications
MCBE'10/MCBC'10 Proceedings of the 11th WSEAS international conference on mathematics and computers in business and economics and 11th WSEAS international conference on Biology and chemistry
Exploiting conflict structures in inconsistent databases
ADBIS'10 Proceedings of the 14th east European conference on Advances in databases and information systems
Consistent answers to boolean aggregate queries under aggregate constraints
DEXA'10 Proceedings of the 21st international conference on Database and expert systems applications: Part II
Range-consistent answers of aggregate queries under aggregate constraints
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Efficient policy-based inconsistency management in relational knowledge bases
SUM'10 Proceedings of the 4th international conference on Scalable uncertainty management
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Detecting suspect answers in the presence of inconsistent information
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Probabilistic query answering over inconsistent databases
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Tractable cases of clean query answering under entity resolution via matching dependencies
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Query rewriting using datalog for duplicate resolution
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Comparable dependencies over heterogeneous data
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Aggregating semantic annotators
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Consistent query answering is the problem of characterizing and computing the semantically correct answers to queries from a database that may not satisfy certain integrity constraints. Consistent answers are characterized as those answers that are invariant under all minimally repaired versions of the original database. We study the problem of repairing databases with respect to denial constraints by fixing integer numerical values taken by attributes. We introduce a quantitative definition of database repair, and investigate the complexity of several decision and optimization problems. Among them, Database Repair Problem (DRP): deciding the existence of repairs within a given distance to the original instance, and CQA: deciding consistency of answers to simple and aggregate conjunctive queries under different semantics. We provide sharp complexity bounds, identifying relevant tractable and intractable cases. We also develop approximation algorithms for the latter. Among other results, we establish: (a) The @D"2^P-hardness of CQA. (b) That DRP is MAXSNP-hard, but has a good approximation. (c) The intractability of CQA for aggregate queries for one database atom denials (plus built-ins), and also that it has a good approximation.