Incomplete Information in Relational Databases
Journal of the ACM (JACM)
On the integrity of databases with incomplete information
PODS '86 Proceedings of the fifth ACM SIGACT-SIGMOD symposium on Principles of database systems
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
Null inclusion dependencies in relational databases
Information and Computation
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
Axiomatisation of functional dependencies in incomplete relations
Theoretical Computer Science
Consistent query answers in inconsistent databases
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database 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
Data Exchange: Semantics and Query Answering
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Closed World Databases Opened Through Null Values
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
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
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
XML data exchange: consistency and query answering
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Schema mappings, data exchange, and metadata management
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Computing cores for data exchange: new algorithms and practical solutions
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange: on the complexity of answering queries with inequalities
Information Processing Letters
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Magic Sets and their application to data integration
Journal of Computer and System Sciences
CWA-solutions for data exchange settings with target dependencies
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On reconciling data exchange, data integration, and peer data management
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Update exchange with mappings and provenance
VLDB '07 Proceedings of the 33rd international conference on Very large data bases
Data exchange in the presence of arithmetic comparisons
EDBT '08 Proceedings of the 11th international conference on Extending database technology: Advances in database technology
The recovery of a schema mapping: bringing exchanged data back
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
Data exchange and schema mappings in open and closed worlds
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Incompleteness in information integration
Proceedings of the VLDB Endowment
Data exchange: query answering for incomplete data sources
Proceedings of the 3rd international conference on Scalable information systems
The ORCHESTRA Collaborative Data Sharing System
ACM SIGMOD Record
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
Complexity of the Stable Model Semantics for Queries on Incomplete Databases
LPNMR '09 Proceedings of the 10th International Conference on Logic Programming and Nonmonotonic Reasoning
The recovery of a schema mapping: Bringing exchanged data back
ACM Transactions on Database Systems (TODS)
The VLDB Journal — The International Journal on Very Large Data Bases
Normalization and optimization of schema mappings
Proceedings of the VLDB Endowment
Towards practical feasibility of core computation in data exchange
Theoretical Computer Science
Answering non-monotonic queries in relational data exchange
Proceedings of the 13th International Conference on Database Theory
On the tradeoff between mapping and querying power in XML data exchange
Proceedings of the 13th International Conference on Database Theory
Static analysis of schema-mappings ensuring oblivious termination
Proceedings of the 13th International Conference on Database Theory
Towards a logical reconstruction of a theory for locally closed databases
ACM Transactions on Database Systems (TODS)
Composition and inversion of schema mappings
ACM SIGMOD Record
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
The complexity of evaluating tuple generating dependencies
Proceedings of the 14th International Conference on Database Theory
Data cleaning and query answering with matching dependencies and matching functions
Proceedings of the 14th International Conference on Database Theory
Data exchange and schema mappings in open and closed worlds
Journal of Computer and System Sciences
Proceedings of the 4th International Workshop on Logic in Databases
ACM Transactions on Database Systems (TODS)
Normalization and optimization of schema mappings
The VLDB Journal — The International Journal on Very Large Data Bases
Data exchange beyond complete data
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
View-based query answering in Description Logics: Semantics and complexity
Journal of Computer and System Sciences
Design by example for SQL table definitions with functional dependencies
The VLDB Journal — The International Journal on Very Large Data Bases
Datalog as a query language for data exchange systems
Datalog'10 Proceedings of the First international conference on Datalog Reloaded
Representation systems for data exchange
Proceedings of the 15th International Conference on Database Theory
The definability abduction problem for data exchange
RR'12 Proceedings of the 6th international conference on Web Reasoning and Rule Systems
Collaborative data sharing via update exchange and provenance
ACM Transactions on Database Systems (TODS)
Data exchange beyond complete data
Journal of the ACM (JACM)
Getting unique solution in data exchange
Proceedings of the VLDB Endowment
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Data exchange is the problem of finding an instance of a target schema, given an instance of a source schema and a specification of the relationship between the source and the target, and answering queries over target instances 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 certain answers semantics may behave in very odd ways.In this paper I explain that this behavior is due to the fact 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. I present a concept of target solutions based on the closed world assumption, and show that the space of all solutions has two extreme points: the canonical universal solution and the core, well studied in data exchange. I show how to define semantics of query answering taking into account incomplete information, and show that the well-known anomalies go away with the new semantics. The paper also contains results on the complexity of query answering, upper approximations to queries (maybe-answers), and various extensions.