The aim of this paper is to introduce a new class of continuous multifunctions, namely upper and lower na-continuous multifunctions, and to obtain some characterizations concerning upper and lower nacontinuous multifunctions. The authors investigate the graph of upper and lower na-continuous multifunctions, and the preservation of properties under upper na-continuous multifunctions. Also, the r...

Various expanded rough set models based on tolerance relations enlarge the application fields of rough set theory. Through generating tolerance relations to fuzzy tolerance relations and combining with dominance relations, a tolerance class of a fuzzy tolerance relation is further decomposed into a positive fuzzy tolerance class, a negative fuzzy tolerance class and a purely fuzzy tolerance cla...

Our main purpose is to introduce the concepts of upper and lower weakly (Λ, sp)- continuous multifunctions. In particular, some characterizations multifunctions are investigated.

The notion of contra continuous functions was introduced and investigated by Dontchev. In this paper, we apply the notion of $beta^{*}$-closed sets in topological space to present and study a new class of functions called contra $beta^{*}$-continuous and almost contra $beta^{*}$-continuous functions as a new generalization of contra continuity.

This paper deals with the concepts of upper and lower almost (Λ, sp)-continuous multifunctions. Moreover, several characterizations multifunctions are investigated.

The lattice Lu of upper semicontinuous convex normal functions with convolution ordering arises in studies of type-2 fuzzy sets. In 2002, Kawaguchi and Miyakoshi [Extended t-norms as logical connectives of fuzzy truth values, Multiple-Valued Logic 8(1) (2002) 53–69] showed that this lattice is a complete Heyting algebra. Later, Harding et al. [Lattices of convex, normal functions, Fuzzy Sets an...