Fuzzy set theory has been extensively applied to extend various database models(conceptual and logical) and resulted in numerous contributions, mainly with respect to the popular relational model or to some related form of it. So this paper reviews fuzzy logical database models, in which fuzzy relational databases are discussed.

Fuzzy set theory has been extensively applied to extend various database models and resulted in numerous contributions, mainly with respect to the popular relational model or to some related form of it. To satisfy the need of modeling complex objects with imprecision and uncertainty, recently many researches have been concentrated on fuzzy object-oriented database models. This paper reviews fuz...

Usable implementations of fuzzy relational database systems are very rare considering the long time of research on the subject. The existing solutions are usually either obsolete or related to a specific application. The research group that authors belong to aims at producing a general system capable of using priority fuzzy logic with databases. The system consists of a fuzzy extension of a rel...

Relational clustering is an extension of clustering for relational data. Fuzzy c-Medoids (FCMdd) based linear fuzzy clustering extracts intrinsic local linear substructures from relational data. However this linear clustering was affected by noise or outliers because of using Euclidean distance. Alternative Fuzzy c-Means (AFCM) is an extension of Fuzzy c-means, in which a modified distance meas...

In the literature, the solution set of a system of bipolar fuzzy relational equations with max-min composition can be characterized by a finite set of maximal and minimal solution pairs. However, some researches presented that determining the consistency of a system of bipolar fuzzy relational equations is NP-complete. Namely, the solution procedure for solving a system of bipolar fuzzy relatio...

 Minimum and maximum operators are two well-known t-norm and s-norm used frequently in fuzzy systems. In this paper, two different types of fuzzy inequalities are simultaneously studied where the convex combination of minimum and maximum operators is applied as the fuzzy relational composition. Some basic properties and theoretical aspects of the problem are derived and four necessary and suffi...

The paper presents the design and implementation of a digital rule-relational fuzzy logic controller. Classical and decomposed logical structures of fuzzy systems are discussed. The second allows a decrease in the hardware cost of the fuzzy system and in the computing time of the final result (fuzzy or crisp), especially when referring to relational systems. The physical architecture consists o...

In the literature, some studies have shown that determining the consistency of bipolar fuzzy relational equations is NP-complete. Namely, the solution procedure for solving a system of bipolar fuzzy relational equations with max-product composition contains a high computational complexity. In this study, some sufficient conditions for consistency of bipolar fuzzy relational equations are propos...

project selection is considered as an important problem in project management. it is multi-criteria in nature and is based on various quantitative and qualitative factors. the main purpose of this paper is to present a new rank-based method for project selection in outranking relation. according to this approach, decision alternatives were clustered in the concordance matrix and the discordance...

One of the disadvantages of the relational model is its disability to model uncertain and incomplete data. The idea to use fuzzy sets and fuzzy logic to extend existing database models to include these possibilities has been utilized since the 1980s. Although this area has been researched for a long time, concrete implementations are rare. Literature contains references to several models of fuz...