Incomplete Information in Relational Databases
Journal of the ACM (JACM)
On the representation and querying of sets of possible worlds
Selected papers of the workshop on Deductive database theory
Horn clauses and database dependencies
Journal of the ACM (JACM)
Problem of Incomplete Information in Relational Databases
Problem of Incomplete Information in Relational Databases
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Data Exchange: Semantics and Query Answering
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Data exchange: getting to the core
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Composing schema mappings: second-order dependencies to the rescue
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange and incomplete information
Proceedings of the twenty-fifth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Composition of mappings given by embedded dependencies
ACM Transactions on Database Systems (TODS)
CWA-solutions for data exchange settings with target dependencies
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
ACM Transactions on Database Systems (TODS)
Towards a theory of schema-mapping optimization
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Reverse data exchange: coping with nulls
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
The recovery of a schema mapping: Bringing exchanged data back
ACM Transactions on Database Systems (TODS)
Towards an algebraic theory of information integration
Information and Computation
Composition with target constraints
Proceedings of the 13th International Conference on Database Theory
Answering non-monotonic queries in relational data exchange
Proceedings of the 13th International Conference on Database Theory
Composing local-as-view mappings: closure and applications
Proceedings of the 13th International Conference on Database Theory
Data correspondence, exchange and repair
Proceedings of the 13th International Conference on Database Theory
Composition and inversion of schema mappings
ACM SIGMOD Record
Proceedings of the 4th International Workshop on Logic in Databases
Data exchange beyond complete data
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Incomplete information and certain answers in general data models
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
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The notion of representation systems describes structures that are algebraically closed under queries. It has recently been realized that representation systems are highly relevant also in the context of data exchange. We extend the notion of representation system to encompass data exchange mappings and their composition. Seen through this lens, two major classes of representation systems emerge, namely homomorphic data exchange systems and strong data exchange systems. The homomorphic "OWA" systems encompass the "classical" part of data exchange. Reasoning is modulo homomorphic equivalence (CQ-equivalence), and only unions of conjunctive queries and monotone data exchange mappings are supported. We then develop some new technical tools that allow us to prove that there is a class of '"CWA" strong representation systems in which reasoning is modulo isomorphic equivalence. These systems are based on conditional tables, and they support first order queries and non-monotonic data exchange mappings specified by a large class of second order dependencies. We achieve this by showing that, under a CWA-interpretation, conditional tables are chaseable with the aforementioned class of second order dependencies, and that the class is closed under composition in the CWA-setting. We also introduce a stricter notion of composability, and show that the class of (first order) source-to-target tuple generating dependencies is closed under the stricter notion of composability.