In this paper, we construct two fuzzy sets using the notions of level subsets and strong level subsets of a given fuzzy set in a ring R. These fuzzy sets turn out to be identical and provide a universal construction of a fuzzy ideal generated by a given fuzzy set in a ring. Using this construction and employing the technique of strong level subsets, we provide the shortest and direct fuzzy set ...

In many practical situation, some of the attribute values for an object may be interval and set-valued. This paper introduces the interval and set-valued information systems and decision systems. According to the semantic relation of attribute values, interval and set-valued information systems can be classified into two categories: disjunctive (Type 1) and conjunctive (Type 2) systems. In this...

Abstract In this paper, a fuzzy PID with new structure is proposed to solve the load frequency control in interconnected power systems. in this study, a new structure and effective of the fuzzy PID-type Load frequency control (LFC) is proposed to solve the load frequency control in interconnected power systems. The main objective is to eliminate the deviations in the frequency of different area...

The paper deals with an extension of aggregation operators from the set of real numbers (or interval [0, 1]) to the set of fuzzy truth values (fuzzy sets in [0, 1]). We define so-called type-2 aggregation operator and show that an extension of ordinary aggregation operator by convolution is a type-2 aggregation operator. Finally we show that ordinary aggregation operator, as well as aggregation...

In many works dealing with knowledge representation, there is a temptation to extend the truth-set with values expressing ignorance and contradiction. This is the case with partial logic and Belnap bilattice logic. This is also true in interval-valued extensions of fuzzy sets. This paper shows that ignorance and contradiction cannot be viewed as additional truth-values nor processed in a truthf...

This paper is a study of fuzzy type theory (FTT) with partial functions. Out of several possibilities we decided tointroduce a special value ”∗” that represents ”undefined”. In the interpretation of FTT, this value lays outside of thecorresponding domain. In the syntax it can be naturally represented by the description operator acting on the empty(fuzzy) set, because choosing an element from it...

In this paper, the texture property “coarseness” is modeled by means of type-2 fuzzy sets, relating representative coarseness measures (our reference set) with the human perception of this texture property. The type-2 approach allows to face both the imprecision in the interpretation of the measure value and the uncertainty about the coarseness degree associated with a measure value. In our stu...