Evaluating Environmental Factors through a BL-Algebra

In this paper a method for environmental evaluation based on type-2 fuzzy sets and a BL-algebra defined therein is illustrated. Introduced by L. Zadeh in 1975, fuzzy sets allow to represent imprecise knowledge in a simple and effective way by carrying out algebraic computations on linguistic elements. In this evaluation model every environmental indicator (security, facilities, environment, social impact, and so on) is a type-2 fuzzy set. This approach has been utilized both to rank the quality of life in some Italian cities and then the environmental quality of four sites for a domestic airport near Reykjavik. As regards the Italian cities this approach produces results similar to those obtained by statistical methods but one gets a linguistic classification of cities and not a numerical one. Also as regards the sites for the airport, the results are similar but the linguistic expressivity is greatly enhanced