9. The method of claim 8 , wherein the first plurality of categories includes categories within a tree of categories.
9. The method of claim 8 , wherein the first plurality of categories includes categories within a tree of categories. 10. The method of claim 9 , wherein modifying the first plurality of categories comprises: based on the entropy value exceeding a minimum threshold, modifying the first plurality of categories to generate the second plurality of categories by replacing at least one category of the first plurality of categories with a parent of the at least one category in the tree of categories.