  We are now prepared to define the revision rule given by a ground model M = &lt;D, I &gt;. In general, given an hypothesis h, let M + h = &lt;D, I′ &gt; be the model of L which agrees with M on the T-free fragment of L, and which is such that I′(T) = h. So M + h is just a classical model for all of L. For any model M + h of all of L and any sentence A if L, let ValM+h(A) be the ordinary classical truth value of A in M + h. 