<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">B</font> be    <a href="trees_2.html#M1" target="_self">Chain</a> of <font color="Maroon">W</font>;<br/>

<b>assume </b><a NAME="E1:34_1_1"/><i><font color="Green">E50</font></i>: 
( <font color="Maroon">B</font> is <a href="trees_2.html#V2" target="_self">Branch-like</a> &amp; <font color="Maroon">B</font> is <a href="xboole_0.html#V1">empty</a> )
 ;<br/>

<b>consider </b><font color="Maroon">t</font> being    <a href="trees_1.html#M1">Element</a> of <font color="Maroon">W</font>;<br/>
<a NAME="E3:34_1_1"/>
( <font color="Maroon">t</font> <a href="hidden.html#R2">in</a> <font color="Maroon">W</font> &amp; ( for <font color="Olive">q</font> being   <a href="finseq_1.html#M2">FinSequence</a> of  <a href="numbers.html#K5">NAT</a>   st <font color="Olive">q</font> <a href="hidden.html#R2">in</a> <font color="Maroon">B</font> holds <br/><font color="Olive">q</font> <a href="trees_1.html#NR3" target="_self">is_a_proper_prefix_of</a> <font color="Maroon">t</font> ) )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:34_1_1"/>
contradiction
 <b>by </b><i>, </i>;<br/>


</div>
