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<b>let </b><font color="Maroon">W</font> be   <a href="classes2.html#NM1">Universe</a>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="cat_1.html#NM1">Object</a> of <span class="p1">(<span class="default"><a href="ens_1.html#K12" target="_self">Ens</a> <font color="Maroon">W</font></span>)</span>;<br/>



<a NAME="E1:50"/>
 <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">W</font>
 
<b>by </b><i><a class="ref" href="classes2.html#T62">CLASSES2:62</a></i>;<br/>
<b>hence </b><a NAME="E2:50"/>
( <font color="Maroon">a</font> is <a href="cat_1.html#V7">initial</a> implies <font color="Maroon">a</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  )
 <b>by </b><i><a class="txt" href="ens_1.html#E10"><i><font color="Green">Lemma34</font></i></a></i>;<br/>


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