A central tenet of modern categorization research is that real-world categories have no defining features, and that features are better thought of as probabilistically related to their category. Nevertheless, the belief in properties that are invariably associated with categories has persisted. One view— psychological essentialism—further states that essential properties and structures constrai...

In this paper a first step in classifying the fuzzy normalsubgroups of a finite group is made. Explicit formulas for thenumber of distinct fuzzy normal subgroups are obtained in theparticular cases of symmetric groups and dihedral groups.

In Data Envelopment Analysis (DEA), it is assumed that the role of each factor is known asinput or output. However, in some cases, there are shared factors that their input versusoutput status is not clearly known. These are flexible measures. In such cases, determiningwhether a factor is input or output is ambiguous. Therefore, using fuzzy concept seems to benecessary.In this paper, a two phas...