Hi,<br><br>While doing some experimentation with Ciao's FD solver, I found some unusual and apparently wrong answers. The version I tried was "Ciao 1.15.0-13646: Fri Nov 4 11:40:25 CET 2011"<br><br>Yo can in fact write constraints like the one below:<br><br>?- X.&gt;.12.<br><br>X attributed '$fd'(X,[[13|67108863]],[]) ?<br><br>The answer is right (if I understand the notation properly), but the same constraint&nbsp; written backwards does not work:<br><br>?- 12.&lt;.X.<br><br>X attributed '$fd'(X,[],[]) ? <br><br>This seems to mean something like "There is no solution for X", which is wrong (although Ciao still responds "yes" for this case).<br><br>In general, any constraint written as &lt;constant&gt; .op. &lt;free var&gt; will suffer the same problem.<br><br>Was this problem known?. If so, is there any correction for it?.<br><br>Thanks. Kind regards,<br><br>Jose<br><br><br>