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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be   <a href="glib_000.html#NM2">_Graph</a>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font> be    <a href="glib_001.html#M3" target="_self">Walk</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>4</sub></font> be    <a href="glib_001.html#M3" target="_self">Walk</a> of <font color="Maroon">c<sub>2</sub></font>;<br/>







<b>assume </b><a NAME="E1:161"/><i><font color="Green">E115</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<b>let </b><font color="Maroon">c<sub>5</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>

<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="161_1"><b>now </b></a><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="161_1_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:161_1_1"/>
( ( not <font color="Maroon">c<sub>5</sub></font> is <a href="abian.html#V1">even</a> &amp; <font color="Maroon">c<sub>5</sub></font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="finseq_1.html#K3">len</a> <font color="Maroon">c<sub>3</sub></font> ) or <font color="Maroon">c<sub>5</sub></font> is <a href="abian.html#V1">even</a> or  not <font color="Maroon">c<sub>5</sub></font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="finseq_1.html#K3">len</a> <font color="Maroon">c<sub>3</sub></font> )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="161_1_1_1"><b>suppose </b></a><a NAME="E1:161_1_1_1"/><i><font color="Green">E116</font></i>: 
( not <font color="Maroon">c<sub>5</sub></font> is <a href="abian.html#V1">even</a> &amp; <font color="Maroon">c<sub>5</sub></font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="finseq_1.html#K3">len</a> <font color="Maroon">c<sub>3</sub></font> )
 ;<br/><div class="add"><b>hence </b><font color="Maroon">c<sub>3</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font> = 
<font color="Maroon">c<sub>4</sub></font> <a href="funct_1.html#K1">.</a> <font color="Maroon">c<sub>5</sub></font>
<b>by </b><i><a class="txt" href="glib_001.html#E1:161"><i><font color="Green">E115</font></i></a>, <a class="ref" href="glib_001.html#D8" target="_self">Def8</a></i>
<br/>.= 
<font color="Maroon">c<sub>4</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font>
<b>by </b><i><a class="txt" href="glib_001.html#E1:161"><i><font color="Green">E115</font></i></a>, <a class="txt" href="glib_001.html#E1:161_1_1_1"><i><font color="Green">E116</font></i></a>, <a class="ref" href="glib_001.html#D8" target="_self">Def8</a></i>
;<br/><br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="161_1_1_2"><b>suppose </b></a><a NAME="E1:161_1_1_2"/><i><font color="Green">E116</font></i>: 
( <font color="Maroon">c<sub>5</sub></font> is <a href="abian.html#V1">even</a> or  not <font color="Maroon">c<sub>5</sub></font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="finseq_1.html#K3">len</a> <font color="Maroon">c<sub>3</sub></font> )
 ;<br/><div class="add"><b>hence </b><font color="Maroon">c<sub>3</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font> = 
<font color="Maroon">c<sub>3</sub></font> <a href="glib_001.html#K3" target="_self">.first()</a> 
<b>by </b><i><a class="ref" href="glib_001.html#D8" target="_self">Def8</a></i>
<br/>.= 
<font color="Maroon">c<sub>4</sub></font> <a href="glib_001.html#K3" target="_self">.first()</a> 
<b>by </b><i><a class="txt" href="glib_001.html#E1:161"><i><font color="Green">E115</font></i></a></i>
<br/>.= 
<font color="Maroon">c<sub>4</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font>
<b>by </b><i><a class="txt" href="glib_001.html#E1:161"><i><font color="Green">E115</font></i></a>, <a class="txt" href="glib_001.html#E1:161_1_1_2"><i><font color="Green">E116</font></i></a>, <a class="ref" href="glib_001.html#D8" target="_self">Def8</a></i>
;<br/><br/></div><b>end;</b></div></div><b>end;</b></div></div><b>end;</b></div>
<b>hence </b><a NAME="E3:161"/>
<font color="Maroon">c<sub>3</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>4</sub></font> <a href="glib_001.html#K5" target="_self">.vertexAt</a> <font color="Maroon">c<sub>5</sub></font>
 ;<br/>


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