Integrity = validity + completeness
ACM Transactions on Database Systems (TODS)
Sound and efficient closed-world reasoning for planning
Artificial Intelligence
Complexity of answering queries using materialized views
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Obtaining Complete Answers from Incomplete Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
On the local closed-world assumption of data-sources
LPNMR'05 Proceedings of the 8th international conference on Logic Programming and Nonmonotonic Reasoning
Representation of partial knowledge and query answering in locally complete databases
LPAR'06 Proceedings of the 13th international conference on Logic for Programming, Artificial Intelligence, and Reasoning
Towards a logical reconstruction of a theory for locally closed databases
ACM Transactions on Database Systems (TODS)
Constraint Propagation for First-Order Logic and Inductive Definitions
ACM Transactions on Computational Logic (TOCL)
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The Closed-World Assumption (CWA) on databases expresses that an atom not in the database is false. A more appropriate assumption for databases that are sound but partially incomplete, is the Local Closed-World Assumption (LCWA), which is a local form of the CWA, expressing that the database is complete in a certain area, called the 'window of expertise'. Databases consisting of a standard database instance augmented with a collection of LCWA's are called locally closed databases. In this paper, we investigate the complexity of certain and possible query answering in such databases. As it tums out that these problems are intractlble, we develop efficient approximate methods to underestimate certain answers and overestimate possible answers. We prove that under certain conditions, our methods produce complete answers.