One can also calculate the derivative of a context free grammar with respect to a given terminal.<p><a href="http:&#x2F;&#x2F;matt.might.net&#x2F;articles&#x2F;parsing-with-derivatives&#x2F;" rel="nofollow">http:&#x2F;&#x2F;matt.might.net&#x2F;articles&#x2F;parsing-with-derivatives&#x2F;</a>