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<div><span class="kw">theorem </span><span class="lab"><font color="Green" title="E29">Th28</font></span>: <a NAME="T29"><span class="comment"><font color="firebrick">:: ENS_1:29</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">V</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">a</font> being   <a href="cat_1.html#NM1" title="CAT_1:NM.1">Object</a> of <span class="p1">(<span class="default"><a href="ens_1.html#K11" title="ENS_1:func.11">Ens</a> <font color="Olive" title="b1">V</font></span>)</span> holds   <a href="cat_1.html#K4" title="CAT_1:func.4">id</a> <font color="Olive" title="b2">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="ens_1.html#K5" title="ENS_1:func.5">id$</a> <span class="p1">(<span class="default"><a href="ens_1.html#K13" title="ENS_1:func.13">@</a> <font color="Olive" title="b2">a</font></span>)</span></div></div>
