Aggregation of equivalence relations

Abstract

Each ofn attributes partitions a set of items into equivalence classes. Aconsistent aggregator of then partitions is defined as an aggregate partition that satisfies an independence condition and a unanimity condition. It is shown that the class of consistent aggregators is precisely the class ofconjunctive aggregators. That is, for each consistent aggregator there is a nonempty subsetN of the attributes such that two items are equivalent in the aggregate partition if and only if they are equivalent with respect to each attribute inN.