Database queries with fuzzy linguistic quantifiers
IEEE Transactions on Systems, Man and Cybernetics
File structures: an analytic approach
File structures: an analytic approach
Algorithms for Multidimensional Partitioning of Static Files
IEEE Transactions on Software Engineering
Fuzzy querying with SQL: extensions and implementation aspects
Fuzzy Sets and Systems - Mathematical Modelling
Fuzzy logic for the management of uncertainty
Fuzzy logic for the management of uncertainty
Fuzzy querying in conventional databases
Fuzzy logic for the management of uncertainty
Fuzzy object-oriented database modeling coupled with fuzzy logic
Fuzzy Sets and Systems
The Grid File: An Adaptable, Symmetric Multikey File Structure
ACM Transactions on Database Systems (TODS)
On Databases with Incomplete Information
Journal of the ACM (JACM)
Multidimensional binary search trees used for associative searching
Communications of the ACM
A relational model of data for large shared data banks
Communications of the ACM
Principles and Applications
The Multilevel Grid File - A Dynamic Hierarchical Multidimensional File Structure
Proceedings of the Second International Symposium on Database Systems for Advanced Applications
Multidimensional Binary Search Trees in Database Applications
IEEE Transactions on Software Engineering
Similarity relations and fuzzy orderings
Information Sciences: an International Journal
A Similarity-Based Unification Model for Flexible Querying
FQAS '02 Proceedings of the 5th International Conference on Flexible Query Answering Systems
Extending Relational Data Access Programming Libraries for Fuzziness: The fJDBC Framework
FQAS '02 Proceedings of the 5th International Conference on Flexible Query Answering Systems
An Indexing Technique for Fuzzy Numerical Data
SUM '07 Proceedings of the 1st international conference on Scalable Uncertainty Management
FQAS'11 Proceedings of the 9th international conference on Flexible Query Answering Systems
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A significant effort has been made in representing imprecise information in database models by using fuzzy set theory. However, the research directed toward access structures to handle fuzzy querying effectively is still at an immature stage. Fuzzy querying involves more complex processing than the ordinary querying does. Additionally, a larger number of tuples are possibly selected by fuzzy conditions in comparison to the crisp ones. It is obvious that the need for fast response time becomes very important when the database system deals with imprecise (fuzzy) data. The current crisp index structures are inappropriate for representing and efficiently accessing fuzzy data. At the same time, in many complex applications such as Expert Database Systems, Multimedia Database Systems, Decision Support Systems, etc., fuzzy queries are usually intermingled with crisp queries. For the effectiveness of fuzzy databases, it is necessary to allow both the non-fuzzy and fuzzy attributes to be indexed together; therefore, a multi-dimensional access structure is required. Beside a suitable access structure, an effective partitioning, representation, and storage of fuzzy data are also necessary for efficient retrieval. In this study we utilise a multi-dimensional data structure, namely Multi Level Grid File (MLGF), for efficiently accessing both crisp and fuzzy data from fuzzy databases. Therefore, we focus on the issue of partitioning, representation and organisation of fuzzy and crisp data at physical database level, i.e., record and file structures, in addition to the design of the access structure. The implementation of the access structure is also described and its comparison with a previously proposed fuzzy access method is given along with the experimental results.