A new method based on a fuzzy outranking relation for supporting collective sorting decisions

The present proposal concerns group sorting problems, which are special kind of multi‐participant classification problems where an ordinal preference is defined on the set of categories. The group sorting problem is transformed into a much better studied group ranking problem. Following ideas from ELECTRE methods, the group member preferences are aggregated in a fuzzy group preference relation, which is a good model of the natural heuristic used by groups for making reasonable decisions. In this model, veto effects combined with majority rules are considered in as tools to reflect basic principles of democracy and respect to important minorities.