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<b>let </b><font color="Maroon">D</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">D</font>;<br/>



<div><b>hereby </b>
<div class="add"><b>assume </b><a NAME="E1:31_1"/>
not <font color="Maroon">A</font> is <a href="realset1.html#V1" target="_self">trivial</a>
 ;<br/><b>then consider </b><font color="Maroon">d1</font> being    <a href="hidden.html#M1">set</a> , <font color="Maroon">d2</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E3:31_1"/><i><font color="Green">E19</font></i>: 
( <font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> )
 <b>and </b><br/><a NAME="E4:31_1"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">d1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">d2</font>
 <b>by </b><i/>;<br/><b>reconsider </b><font color="Maroon">d1</font> = <font color="Maroon">d1</font>, <font color="Maroon">d2</font> = <font color="Maroon">d2</font> as    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font> <b>by </b><i/>;<br/><b>take </b><font color="Maroon">d1</font> = <font color="Maroon">d1</font>;<br/><b>take </b><font color="Maroon">d2</font> = <font color="Maroon">d2</font>;<br/><b>thus </b><a NAME="E6:31_1"/>
( <font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Maroon">d1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">d2</font> )
 <b>by </b><i>, </i>;<br/></div>
<b>end;</b></div>

<b>thus </b><a NAME="E2:31"/>
(  ex <font color="Olive">d1</font>, <font color="Olive">d2</font> being   <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font> st <br/>( <font color="Olive">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Olive">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Olive">d1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Olive">d2</font> ) implies  not <font color="Maroon">A</font> is <a href="realset1.html#V1" target="_self">trivial</a> )
 <b>by </b><i/>;<br/>


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