6735589 Method of reducing dimensionality of a set of attributes used to characterize a sparse data set

A software facility for analyzing each of a plurality of groups of items is described. The facility retrieves information identifying, for each of a plurality of groups, items that are members of the group. For each group, the facility analyzes attributes of the items of the group to identify attributes that distinguish items that are members of the group from items that are not members of the group.