Restructure Tree of Attributes
In order to avoid combinatorial explosion in DEXi models, it is strongly advised to structure the tree of attributes so that each aggregate attribute has only two or three immediate descendants. Whenever you encounter an aggregate attribute with four descendants, you may want to consider restructuring the tree below that attribute. Usually, there are several ways to do this:
In all cases, you should regroup the lower-level attributes and introduce one or two new aggregate attributes, denoted by .
Usually, the ‘right’ structure is the one that appears the most ‘logical’ so that:
it groups together similar or related attributes, and
it is easy to give names to the newly created attributes.