  One must be careful about the interaction between definite descriptions and modal operators, just as between them and negation. For instance,  \(D(\atoi x\Diamond \phi (x)) \supset \Diamond D(\atoi x\phi (x))\)  is valid, but its converse is not. For a more concrete example of modal/description interaction, suppose \(K(x)\) is a formula expressing that \(x\) is King of France. In the present state,  \([\lambda x\,\Diamond E(x)](\atoi xK(x))\)  is false, because the definite description has no designation, but  \(\Diamond [\lambda x\,E(x)](\atoi xK(x))\) is true, because there is an alternative (earlier) state in which the definite description designates an existent object.