A fuzzy implication, commonly defined as a two-place operation on the unit interval, is an extension of the classical binary implication. It plays important roles in both mathematical and applied sides of fuzzy set theory. Besides the basic axioms, there are many potential fuzzy implication axioms, among which eight are widely used in the literature. Different fuzzy implications satisfying diff...

The goal of this paper is to consider properties of the composition of interval-valued fuzzy relations which were introduced by L.A. Zadeh in 1975. Fuzzy set theory turned out to be a useful tool to describe situations in which the data are imprecise or vague. Interval-valued fuzzy set theory is a generalization of fuzzy set theory which was introduced also by Zadeh in 1965. This paper generali...

The psychology of concepts has been undergoing significant changes since the early 1970s, when the classical view of concepts was seriously challenged by convincing experimental evidence that conceptual categories never have sharp boundaries. Some researchers recognized already in the early 1970s that fuzzy set theory and fuzzy logic were potentially suitable for modeling of concepts and obtain...

The concept of quasi-coincidence of a fuzzy interval value in an interval valued fuzzy set is considered. In fact, this concept is a generalized concept of the quasi-coincidence of a fuzzy point in a fuzzy set. By using this new concept, the authors define the notion of interval valued (∈,∈ ∨q)fuzzy h-ideals of hemirings and study their related properties. In addition, the authors also extend t...

This paper is a reply to the article entitled Elkan’s Theoretical Argument, Reconsidered by Prof. Enric Trillas and Prof. Claudi Alsina. I would like to express my thanks to Dr. Piero Bonissone for inviting me to write this paper and for showing me the article by Trillas and Alsina in advance of its publication. Ever since mathematical studies of fuzziness began with a 1965 paper entitled Fuzzy...

The paper discusses some core topics which present open problems in the field of mathematical fuzzy logic and in the foundations of fuzzy set theory. It may reasonably be assumed that these problems shall have great influence for the future development of fuzzy logic within the next decade.

A complex fuzzy set is a set whose membership values are vectors in the unit circle in the complex plane. This paper establishes the orthogonality relation of complex fuzzy sets. Two complex fuzzy sets are said to be orthogonal if their membership vectors are perpendicular. We present the basic properties of orthogonality of complex fuzzy sets and various results on orthogonality with respect t...

Based on fuzzy set theory, flexible querying enables users to express preferences inside requirements. Quantifications and preferences on data have led us to define the notion of fuzzy integers ( f). This framework has been extended (to f and f ) in order to dealing with queries based on difference or division operations. In this paper we study how to define fuzzy order relations between such f...

This paper addresses the design of a robust set-based interval observer for nonlinear discrete-time system affected by uncertainty (state disturbance and measurement noise) using Takagi-Sugeno (TS) fuzzy model including an unmeasurable premise variable. The effect variable uncertainties is considered as unknown but bounded nature, i.e., in set-membership framework. A zonotopic representation se...