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<b>let </b><font color="Maroon">E</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">A</font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">E</font>;<br/>



<b>thus </b><a NAME="E1:35"/>
( <font color="Maroon">A</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A</font> <a href="subset_1.html#K3" target="_self">`</a>  implies <font color="Maroon">A</font> <a href="hidden.html#R1">=</a>  <a href="subset_1.html#K1" target="_self">{}</a> <font color="Maroon">E</font> )
 <b>by </b><i><a class="ref" href="xboole_1.html#T38">XBOOLE_1:38</a></i>;<br/>

<a NAME="E2:35"/>
<font color="Maroon">A</font> <a href="hidden.html#R2">in</a>  <a href="zfmisc_1.html#K1">bool</a> <font color="Maroon">E</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E3:35"/>
( <font color="Maroon">A</font> <a href="hidden.html#R1">=</a>  <a href="subset_1.html#K1" target="_self">{}</a> <font color="Maroon">E</font> implies <font color="Maroon">A</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A</font> <a href="subset_1.html#K3" target="_self">`</a>  )
 <b>by </b><i><a class="ref" href="zfmisc_1.html#D1">ZFMISC_1:def 1</a></i>;<br/>


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