6. The method recited in claim 1 , wherein the one or more distance metrics include at least one distance metric that quantifies a semantic similarity between individual rules in the first grammar and individual rules in the second grammar.
7. The method recited in claim 6 , wherein calculating the at least one distance metric that quantifies the semantic similarity between the individual rules in the first grammar and the individual rules in the second grammar comprises calculating a normalized Hamming distance between the individual rules in the first grammar and the individual rules in the second grammar that have an equal length.