On semantic issues connected with incomplete information databases
ACM Transactions on Database Systems (TODS)
Extending the database relational model to capture more meaning
ACM Transactions on Database Systems (TODS)
On Databases with Incomplete Information
Journal of the ACM (JACM)
Relational database: a practical foundation for productivity
Communications of the ACM
Principles of Database Systems
Principles of Database Systems
Logic and Data Bases
Null values in data base management a denotational semantics approach
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
ACM SIGMOD Record
Incomplete information and the join operation in database machines
ACM '87 Proceedings of the 1987 Fall Joint Computer Conference on Exploring technology: today and tomorrow
Fuzzy functional dependencies and lossless join decomposition of fuzzy relational database systems
ACM Transactions on Database Systems (TODS)
Imprecise schema: a rationale for relations with embedded subrelations
ACM Transactions on Database Systems (TODS)
Indefinite and maybe information in relational databases
ACM Transactions on Database Systems (TODS)
A family of incomplete relational database models
VLDB '89 Proceedings of the 15th international conference on Very large data bases
ANNA '91 Proceedings of the conference on Analysis of neural network applications
Statistical inference of unknown attribute values in databases
CIKM '93 Proceedings of the second international conference on Information and knowledge management
Towards a relational model for exclusively disjunctive information
CSC '93 Proceedings of the 1993 ACM conference on Computer science
How to modify SQL queries in order to guarantee sure answers
ACM SIGMOD Record
ACM Transactions on Database Systems (TODS)
MAYBE algebra operators in database machine architecture
ACM '86 Proceedings of 1986 ACM Fall joint computer conference
An intelligent approach to handling imperfect information in concept-based natural language queries
ACM Transactions on Information Systems (TOIS)
Searching a minimal semantically-equivalent subset of a set of partial values
The VLDB Journal — The International Journal on Very Large Data Bases
IEEE Transactions on Knowledge and Data Engineering
A Generalized Relational Model for Indefinite and Maybe Information
IEEE Transactions on Knowledge and Data Engineering
Reliability of Answers to Queries in Relational Databases
IEEE Transactions on Knowledge and Data Engineering
An Exploration of Relationships Among Exclusive Disjunctive Data
IEEE Transactions on Knowledge and Data Engineering
Information Source Tracking Method: Efficiency Issues
IEEE Transactions on Knowledge and Data Engineering
Incomplete Relational Database Models Based on Intervals
IEEE Transactions on Knowledge and Data Engineering
Dependency Satisfaction in Databases with Incomplete Information
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
Closed World Databases Opened Through Null Values
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
Incomplete Information in Relational Temporal Databases
VLDB '92 Proceedings of the 18th International Conference on Very Large Data Bases
Decision Support with Imprecise Data for Consumers
Soft-Ware 2002 Proceedings of the First International Conference on Computing in an Imperfect World
Temporal Databases with Null Values
DEXA '00 Proceedings of the 11th International Conference on Database and Expert Systems Applications
Update semantics for incomplete databases
VLDB '85 Proceedings of the 11th international conference on Very Large Data Bases - Volume 11
On the correctness criteria of fine-grained access control in relational databases
VLDB '07 Proceedings of the 33rd international conference on Very large data bases
The VLDB Journal — The International Journal on Very Large Data Bases
AuditGuard: a system for database auditing under retention restrictions
Proceedings of the VLDB Endowment
Tolerant division queries and possibilistic database querying
Fuzzy Sets and Systems
Consistency enforcement in databases
Proceedings of the 2nd international conference on Semantics in databases
A data model based on paraconsistent intuitionistic fuzzy relations
ISMIS'05 Proceedings of the 15th international conference on Foundations of Intelligent Systems
Auditing a database under retention policies
The VLDB Journal — The International Journal on Very Large Data Bases
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Database relations which possibly contain maybe-tuples and null values of type “value at present unknown” are studied. Maybe-tuples and null values are formally interpreted by our notion of representation, which uses classical notions of predicate logic, elaborates Codd's proposal of maybe-tuples, and adopts Reiter's concept of a closed world. Precise notions of information content and redundancy, associated with our notion of representation, are investigated. Extensions of the relational algebra to relations with maybe-tuples and null values are proposed. Our extensions are essentially Codd's, with some modifications. It is proved that these extensions have natural properties which are formally stated as being adequate and restricted.By the treatment of difference and division, our formal framework can be used even for operations that require “negative information.” Finally, extensions of update operations are discussed.