the idea of difference sequences of real (or complex) numbers was introducedby ki zmaz cite{kizmaz}. in this paper, using the difference operator and alacunary sequence, we introduce and examine the class of sequence $bv_{theta}left(  delta,mathcal{f}right)  .$ we study some of its properties likesolidity, symmetricity, etc.

This paper first improves Chen and Hsieh’s definition of generalized fuzzy numbers, which makes it the generalization of definition of fuzzy numbers. Secondly, in terms of the generalized fuzzy numbers set, we introduce two different kinds of orders and arithmetic operations and metrics based on the λ-cutting sets or generalized λ-cutting sets, so that the generalized fuzzy numbers are integrat...

ranking fuzzy numbers plays a very important role in decision making and some other fuzzy application systems. many different methods have been proposed to deal with ranking fuzzy numbers. constructing ranking indexes based on the centroid of fuzzy numbers is an important case. but some weaknesses are found in these indexes. the purpose of this paper is to give a new ranking index to rank vario...