Hierarchies of aggregation operators.

Resumen

This article deals with hierarchies of operators. In particular, we will analyze the problem of amalgamating individual opinions into a single group opinion, based upon hierarchical intensity aggregation rules. Our main goal is to decide whether hierarchical amalgamations are supported from an ethical and rational point of view. We will consider two different hierarchical procedures: cover-based hierarchical aggregations and ordered hierarchical aggregations, focusing here our attention to ordered hierarchical aggregations of OWA operators. In particular, we will obtain that basic key properties propagate under both hierarchical amalgamation rules, in the sense that the procedure itself will verify such properties whenever they are assumed for every partial amalgamation defining such a hierarchical procedure.