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<div><span class="kw">theorem </span><a NAME="T18"><span class="comment"><font color="firebrick">:: EXCHSORT:18</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">a</font> being   <a href="ordinal1.html#NM3" title="ORDINAL1:NM.3">Ordinal</a><br/>  for <font color="Olive" title="b2">A</font> being   <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>   <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a>  holds  <font color="Olive" title="b2">A</font> is <font color="Olive" title="b1">a</font> <a href="exchsort.html#V2" title="EXCHSORT:attr.2">-based</a>  ;<br/></div></div>
