A Proof Procedure for Data Dependencies
Journal of the ACM (JACM)
Incomplete Information in Relational Databases
Journal of the ACM (JACM)
A guide to the SQL standard (2nd ed.)
A guide to the SQL standard (2nd ed.)
On the representation and querying of sets of possible worlds
Selected papers of the workshop on Deductive database theory
A semantics for complex objects and approximate answers
Journal of Computer and System Sciences
Using powerdomains to generalize relational databases
Theoretical Computer Science
Theoretical Computer Science
Discrete Mathematics - Algebraic graph theory; a volume dedicated to Gert Sabidussi
Models of approximation in databases
Theoretical Computer Science - Special issue: database theory
Complexity of answering queries using materialized views
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Logical approaches to incomplete information: a survey
Logics for databases and information systems
On semantic issues connected with incomplete information databases
ACM Transactions on Database Systems (TODS)
EXPRESS: a data EXtraction, Processing, and Restructuring System
ACM Transactions on Database Systems (TODS)
The Clio project: managing heterogeneity
ACM SIGMOD Record
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Reformulation of XML Queries and Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
The complexity of relational query languages (Extended Abstract)
STOC '82 Proceedings of the fourteenth annual ACM symposium on Theory of computing
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Locally consistent transformations and query answering in data exchange
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange: getting to the core
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2003
Schema mappings, data exchange, and metadata management
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Clio grows up: from research prototype to industrial tool
Proceedings of the 2005 ACM SIGMOD international conference on Management of data
Data exchange: semantics and query answering
Theoretical Computer Science - Database theory
Composing schema mappings: Second-order dependencies to the rescue
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2004
The complexity of data exchange
Proceedings of the twenty-fifth 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
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)
XML data exchange: Consistency and query answering
Journal of the ACM (JACM)
Efficient core computation in data exchange
Journal of the ACM (JACM)
Towards a theory of schema-mapping optimization
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Answering aggregate queries in data exchange
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
Query languages for data exchange: beyond unions of conjunctive queries
Proceedings of the 12th International Conference on Database Theory
Logical foundations of relational data exchange
ACM SIGMOD Record
Generalized schema-mappings: from termination to tractability
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
The recovery of a schema mapping: Bringing exchanged data back
ACM Transactions on Database Systems (TODS)
On chase termination beyond stratification
Proceedings of the VLDB Endowment
Normalization and optimization of schema mappings
Proceedings of the VLDB Endowment
Data exchange: On the complexity of answering queries with inequalities
Information Processing Letters
Answering non-monotonic queries in relational data exchange
Proceedings of the 13th International Conference on Database Theory
Logic and data exchange: which solutions are "good" solutions?
LOFT'08 Proceedings of the 8th international conference on Logic and the foundations of game and decision theory
Relational and XML Data Exchange
Relational and XML Data Exchange
Data exchange and schema mappings in open and closed worlds
Journal of Computer and System Sciences
Computing universal models under guarded TGDs
Proceedings of the 15th International Conference on Database Theory
Solutions and query rewriting in data exchange
Information and Computation
Taming the infinite chase: query answering under expressive relational constraints
Journal of Artificial Intelligence Research
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Data exchange deals with translating data structured in some source format into data structured in some target format, given a specification of the relationship between the source and the target and possibly constraints on the target; and answering queries over the target in a way that is semantically consistent with the information in the source. Theoretical foundations of data exchange have been actively explored recently. It was also noticed that the standard semantics for query answering in data exchange may lead to counterintuitive or anomalous answers. In the present article, we explain that this behavior is due to the fact that solutions can contain invented information (information that is not related to the source instance), and that the presence of incomplete information in target instances has been ignored. In particular, proper query evaluation techniques for databases with nulls have not been used, and the distinction between closed and open world semantics has not been made. We present a concept of solutions, called CWA-solutions, that is based on the closed world assumption. For data exchange settings without constraints on the target, the space of CWA-solutions has two extreme points: the canonical universal solution (the maximal CWA-solution) and the core of the universal solutions (the minimal CWA-solution), both of them well studied in data exchange. In the presence of constraints on the target, the core of the universal solutions is still the minimal CWA-solution, but there may be no unique maximal CWA-solution. We show how to define the semantics of query-answering taking into account incomplete information, and show that some of the well-known anomalies go away with the new semantics. The article also contains results on the complexity of query-answering, upper approximations to queries (maybe-answers), and various extensions.