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<b>let </b><font color="Maroon">T1</font> be   <a href="trees_1.html#NM1">Tree</a>, <font color="Maroon">T2</font> be   <a href="trees_1.html#NM1">Tree</a>;<br/>

<b>assume </b><a NAME="E1:132"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">T1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">T2</font>
 ;<br/>

<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a><br/>

<b>assume </b><a NAME="E2:132"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="trees_3.html#K14" target="_self">^</a> <font color="Maroon">T1</font>
 ;<br/>

<b>then reconsider </b><font color="Maroon">p</font> = <font color="Maroon">x</font> as    <a href="trees_1.html#M1">Element</a> of  <a href="trees_3.html#K14" target="_self">^</a> <font color="Maroon">T1</font> ;<br/>
<a NAME="E4:132"/>
( <font color="Maroon">p</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  or  ex <font color="Olive">q</font> being  <a href="finseq_1.html#NM1">FinSequence</a> st <br/>( <font color="Olive">q</font> <a href="hidden.html#R2">in</a> <font color="Maroon">T1</font> &amp; <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_1.html#K12">&lt;*</a><span class="default">0</span><a href="finseq_1.html#K12">*&gt;</a></span> <a href="finseq_1.html#K7">^</a> <font color="Olive">q</font> ) )
 
<b>by </b><i><a class="ref" href="trees_3.html#T15" target="_self">Th15</a></i>;<br/>
<b>hence </b><a NAME="E5:132"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="trees_3.html#K14" target="_self">^</a> <font color="Maroon">T2</font>
 <b>by </b><i><a class="ref" href="trees_3.html#T17" target="_self">Th17</a>, <a class="ref" href="trees_3.html#T15" target="_self">Th15</a></i>;<br/>


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