Using fuzzy sets in flexible querying: why and how?
Flexible query answering systems
An overview of fuzzy quantifiers. (I). Interpretations
Fuzzy Sets and Systems
Top-k selection queries over relational databases: Mapping strategies and performance evaluation
ACM Transactions on Database Systems (TODS)
Proceedings of the 17th International Conference on Data Engineering
Preferences; Putting More Knowledge into Queries
VLDB '87 Proceedings of the 13th International Conference on Very Large Data Bases
Preference formulas in relational queries
ACM Transactions on Database Systems (TODS)
Preference SQL: design, implementation, experiences
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
About quotient and division of crisp and fuzzy relations
Journal of Intelligent Information Systems
On a Parameterized Antidivision Operator for Database Flexible Querying
DEXA '08 Proceedings of the 19th international conference on Database and Expert Systems Applications
Database preferences queries: a possibilistic logic approach with symbolic priorities
FoIKS'08 Proceedings of the 5th international conference on Foundations of information and knowledge systems
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In this paper, we are interested in taking preferences into account for a family of queries inspired by the relational division. A division query aims at retrieving the elements associated with a specified set of values and usually the results remain not discriminated. So, we suggest the introduction of preferences inside such queries with the following specificities: (i) the user gives his/her preferences in an ordinal way and (ii) the preferences apply to the divisor which is defined as a hierarchy of sets. Different uses of the hierarchy are investigated, which leads to queries conveying different semantics and the property of the result in terms of a quotient is studied. Special attention is paid to the implementation of such extended division queries using a regular database management system along which some experiments to support the feasibility of the approach. Moreover, the issue of empty or overabundant answers is dealt with.