;\;} {Zip}(x)z_1] {\:\;{\Rightarrow}\:\;}{}$\
        $ [{\forall\,y,z_2\;\;} {LivesIn}(y,s) \land {Zip}(y)z_2 \land {Digit}(1,z_1) {Digit}(1,z_2) ]$.<br />

    3.  ${\forall\,x,y,s\;\;} {State}(s) \land {LivesIn}(x,s) \land {LivesIn}(y,s) {\:\;{\Rightarrow}\:\;}{Digit}(1,{Zip}(x){Zip}(y))$.<br />

    4.  ${\forall\,x,y,s\;\;} {State}(s) \land {LivesIn}(x,s) \land {LivesIn}(y,s) {\:\;{\Rightarrow}\:\;}{}$\
        ${Digit}(1,{Zip}(x)) {Digit}(1,{Zip}(y))$.
<br />
</p>
    </div>
</div>

<p><br /></p>

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