21. The method of claim 18 , comprising associating, for at least one node in the first proposition tree, a word having a relationship to the at least one node to form a first augmented proposition tree.
21. The method of claim 18 , comprising associating, for at least one node in the first proposition tree, a word having a relationship to the at least one node to form a first augmented proposition tree. 23. The method of claim 21 , wherein the relationship is a synonym, hypernym, hyponym, or substitutable label relationship.