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<div><span class="kw">theorem </span><a NAME="T15"><span class="comment"><font color="firebrick">:: PREFER_1:15</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">X</font> being   non  <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>   <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a> <br/>  for <font color="Olive" title="b2">R</font> being   <a href="relset_1.html#NM2" title="RELSET_1:NM.2">Relation</a> of <font color="Olive" title="b1">X</font> holds  <font color="Olive" title="b2">R</font> <a href="relset_1.html#K3" title="RELSET_1:func.3">~</a>  <a href="relset_1.html#R2" title="RELSET_1:pred.2">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Olive" title="b2">R</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a></span>)</span> <a href="relset_1.html#K3" title="RELSET_1:func.3">~</a></span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </div></div>
