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<b>assume </b><a NAME="E1:47_1_1"/>
not  <a href="setfam_1.html#K7" target="_self">COMPLEMENT</a> <font color="Maroon">F</font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/>

<a NAME="E2:47_1_1"/><b>then </b>
 ex <font color="Olive">x</font> being  <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">X</font> st <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="setfam_1.html#K7" target="_self">COMPLEMENT</a> <font color="Maroon">F</font>
 
<b>by </b><i><a class="ref" href="subset_1.html#T10">SUBSET_1:10</a></i>;<br/>
<b>hence </b><a NAME="E3:47_1_1"/>
contradiction
 <b>by </b><i/>;<br/>


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