t least one entity
&gt; &gt; ;; ?x, and hence ?x is an instance-of Entity.  Hence, by the axiom
&gt; &gt; ;; above for instance-of, Entity must be a class (since only classes
&gt; &gt; ;; have instances).
&gt; &gt;
&gt; &gt; (documentation "AXIOM:  Every class is a subclass of Entity.")
&gt; &gt;
&gt; &gt; (forall (?c)
&gt; &gt;         (=&gt; (Class ?c)
&gt; &gt;             (subclass-of ?c Entity)))
&gt; &gt;
&gt; &gt; (documentation "AXIOM: The has relation holds between entities.")
&gt; &gt;
&gt; &gt; (