18. The device of claim 17 , wherein the word groups are descriptions of items in a catalog and wherein the relationship for a particular word is a common reference of two products in the catalog for which corresponding descriptions each contain the particular word.
18. The device of claim 17 , wherein the word groups are descriptions of items in a catalog and wherein the relationship for a particular word is a common reference of two products in the catalog for which corresponding descriptions each contain the particular word. 20. The device of claim 18 , wherein the common reference is a common purchase of the two products.