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<b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">A</font> be   <a href="ordinal1.html#NM2">Ordinal</a>;<br/>



<b>consider </b><font color="Maroon">a</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">X</font>;<br/>
<b>assume </b><a NAME="E2:35"/><i><font color="Green">E19</font></i>: 
( <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A</font> &amp; <font color="Maroon">X</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  )
 ;<br/>

<a NAME="E3:35"/><b>then </b>
<font color="Maroon">a</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 
;<br/>
<b>then consider </b><font color="Maroon">Y</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E5:35"/><i><font color="Green">E21</font></i>: 
( <font color="Maroon">Y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> &amp; ( for <font color="Olive">a</font> being   <a href="hidden.html#M1">set</a>   holds <br/>(  not <font color="Olive">a</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> or  not <font color="Olive">a</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font> ) ) )
 <b>by </b><i><a class="ref" href="tarski.html#T7">TARSKI:7</a></i>;<br/>
<a NAME="E6:35"/>
<font color="Maroon">Y</font> is   <a href="ordinal1.html#NM2">Ordinal</a>
 
<b>by </b><i>, <a class="txt" href="ordinal1.html#E5:35"><i><font color="Green">E21</font></i></a>, </i>;<br/>
<b>then consider </b><font color="Maroon">C</font> being   <a href="ordinal1.html#NM2">Ordinal</a><b> such that </b><br/><a NAME="E8:35"/><i><font color="Green">E22</font></i>: 
<font color="Maroon">C</font> <a href="hidden.html#R1">=</a> <font color="Maroon">Y</font>
 ;<br/>
<b>take </b>
<font color="Maroon">C</font>
;<br/>

<b>thus </b><a NAME="E9:35"/>
<font color="Maroon">C</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 <b>by </b><i><a class="txt" href="ordinal1.html#E5:35"><i><font color="Green">E21</font></i></a>, <a class="txt" href="ordinal1.html#E8:35"><i><font color="Green">E22</font></i></a></i>;<br/>

<b>let </b><font color="Maroon">B</font> be   <a href="ordinal1.html#NM2">Ordinal</a>;<br/>

<b>assume </b><a NAME="E10:35"/>
<font color="Maroon">B</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 ;<br/>

<a NAME="E11:35"/><b>then </b>
not <font color="Maroon">B</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font>
 
<b>by </b><i><a class="txt" href="ordinal1.html#E5:35"><i><font color="Green">E21</font></i></a>, <a class="txt" href="ordinal1.html#E8:35"><i><font color="Green">E22</font></i></a></i>;<br/>
<a NAME="E12:35"/><b>then </b>
( <font color="Maroon">B</font> <a href="hidden.html#R1">=</a> <font color="Maroon">C</font> or <font color="Maroon">C</font> <a href="hidden.html#R2">in</a> <font color="Maroon">B</font> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E13:35"/>
<font color="Maroon">C</font> <a href="ordinal1.html#R1" target="_self">c=</a> <font color="Maroon">B</font>
 <b>by </b><i/>;<br/>


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