                                      (= ?e ?e')))))))
&gt; &gt; &gt;
&gt; &gt; &gt; Now I think we're getting there.
&gt; &gt; &gt; But even more is needed after the "&lt;=&gt;" to assure that:
&gt; &gt; &gt; 1) The same giving does not have more than one giver.
&gt; &gt; &gt; 2) The same giving does not have more than one given
&gt; &gt; &gt; 3) The same giving does not have more than one receiver.
&gt; &gt; 
&gt; &gt; MW:  This actually gets to the heart of the issue quite nicely,
&gt; &gt;      and prov