Hm. Regan et al., A proposal for fuzzy International Union for the Conservation of Nature (IUCN) categories and criteria, BIOL CONSER, 92(1), 2000, pp. 101-108
The classification of endangered species uses categories "extinct in the wi
ld", "endangered" and so on that are intrinsically vague. This vagueness pr
esents various problems for those trying to classify species. The usual way
of dealing with this vagueness is to eliminate it by providing precise def
initions of the categories in question. In this paper we propose a fuzzy se
t-theoretic alternative that respects the inherent vagueness of the crucial
categories without compromising the utility of the classification scheme.
Moreover, we argue that it leads to intuitively more appropriate classifica
tions in many cases. (C) 1999 Elsevier Science Ltd. All rights reserved.