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<b>let </b><font color="Maroon">W</font> be   <a href="trees_1.html#NM1">Tree</a>;<br/><b>let </b><font color="Maroon">L</font> be    <a href="trees_2.html#M2" target="_self">Level</a> of <font color="Maroon">W</font>;<br/>



<b>consider </b><font color="Maroon">n</font> being    <a href="subset_1.html#M2">Element</a> of  <a href="numbers.html#K5">NAT</a> <b> such that </b><br/><a NAME="E2:22"/><i><font color="Green">E50</font></i>: 
<font color="Maroon">L</font> <a href="hidden.html#R1">=</a> <span class="p1">{<span class="default"> <font color="Olive">w</font> where <font color="Olive">w</font> is    <a href="trees_1.html#M1">Element</a> of <font color="Maroon">W</font> :  <a href="finseq_1.html#K3">len</a> <font color="Olive">w</font> <a href="hidden.html#R1">=</a> <font color="Maroon">n</font> </span>}</span> 
 <b>by </b><i/>;<br/>
<b>take </b>
<font color="Maroon">n</font>
;<br/>

<b>thus </b><a NAME="E3:22"/>
<font color="Maroon">L</font> <a href="hidden.html#R1">=</a> <font color="Maroon">W</font> <a href="trees_2.html#K2" target="_self">-level</a> <font color="Maroon">n</font>
 <b>by </b><i/>;<br/>


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