12. The system of claim 9 , wherein a first edge in the first augmented proposition tree matches a second edge in the second proposition tree in response to a semantic relationship associated with the first edge being substitutable for the semantic relationship associated with the second edge.
9. The system of claim 5 , wherein the matching module is configured to determine the first similarity value by determining a number of nodes and a number of edges that match between the first augmented proposition tree and the second proposition tree.