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<div><span class="kw">theorem </span><span class="lab"><font color="Green" title="E8">Th9</font></span>: <a NAME="T9"><span class="comment"><font color="firebrick">:: ZFREFLE1:9</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">M1</font>, <font color="Olive" title="b2">M2</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>   st <font color="Olive" title="b1">M1</font> <a href="zfrefle1.html#R3" title="ZFREFLE1:pred.3">is_elementary_subsystem_of</a> <font color="Olive" title="b2">M2</font> holds <br/><font color="Olive" title="b1">M1</font> <a href="zfrefle1.html#R2" title="ZFREFLE1:pred.2">&lt;==&gt;</a> <font color="Olive" title="b2">M2</font></div></div>
