Decision-making in semi-democratic contexts

A general problem, which may concern practical contexts of different nature, is to aggregate multi-experts rank- ings on a set of alternatives into a single fused ranking. Aggregation should also take into account the experts’ importance, which may not necessarily be the same for all of them. We synthetically define this context as semi- democratic. The main aim of the paper is the analysis of the possible semi-democratic paradigms that can be conceived when the experts’ importance is not the same: (i) the importance is described by means of a weighting vector; (ii) the importance is expressed by a weak order on the set of experts; (iii) the importance is described by a weak order on the set of experts with additional information on the ordinal proximities among them. The three paradigms can be applied in different decision-making situations, where some experts perform multiple assignments. In this paper various situations are discussed and analyzed in detail. A series of examples, in the field of interior design of a new car, will complement the description.