gt; &gt; the constraint
&gt; &gt; &gt;
&gt; &gt; &gt; (=&gt;
&gt; &gt; &gt;    (and
&gt; &gt; &gt;      (instance ?X Employee)
&gt; &gt; &gt;      (birthTime ?X ?BTIME)
&gt; &gt; &gt;      (deathTime ?X ?DTIME))
&gt; &gt; &gt;    (greaterThan ?DTIME ?BTIME))
&gt; &gt;
&gt; &gt;MW: Well that is fine of course (not wrong). However, in this case
&gt; &gt;either all are going to be right, or wrong. So my strategy would be
&gt; &gt;to eyeball the resultant data and do the same test, rather than code
&gt; &gt;and