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<b>let </b><font color="Maroon">G1</font> be   <a href="glib_000.html#NM2">_Graph</a>, <font color="Maroon">G2</font> be   <a href="glib_000.html#NM2">_Graph</a>;<br/>

<b>assume </b><a NAME="E1:50"/><i><font color="Green">E30</font></i>: 
<font color="Maroon">G1</font> <a href="glib_000.html#R5">==</a> <font color="Maroon">G2</font>
 ;<br/>

<b>let </b><font color="Maroon">u1</font> be   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">G1</font>, <font color="Maroon">v1</font> be   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">G1</font>;<br/>

<b>assume </b><a NAME="E2:50"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">u1</font>,<font color="Maroon">v1</font> <a href="chord.html#R1" target="_self">are_adjacent</a> 
 ;<br/>

<b>let </b><font color="Maroon">u2</font> be   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">G2</font>, <font color="Maroon">v2</font> be   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">G2</font>;<br/>

<b>assume </b><a NAME="E3:50"/><i><font color="Green">E53</font></i>: 
( <font color="Maroon">u1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">u2</font> &amp; <font color="Maroon">v1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v2</font> )
 ;<br/>

<b>consider </b><font color="Maroon">e</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E5:50"/><i><font color="Green">E56</font></i>: 
<font color="Maroon">e</font> <a href="glib_000.html#R1">Joins</a> <font color="Maroon">u1</font>,<font color="Maroon">v1</font>,<font color="Maroon">G1</font>
 <b>by </b><i><a class="ref" href="chord.html#T7" target="_self">Th7</a>, <a class="ref" href="chord.html#T4" target="_self">Th4</a></i>;<br/>
<a NAME="E6:50"/>
<font color="Maroon">e</font> <a href="glib_000.html#R1">Joins</a> <font color="Maroon">u2</font>,<font color="Maroon">v2</font>,<font color="Maroon">G2</font>
 
<b>by </b><i><a class="ref" href="chord.html#T8" target="_self">Th8</a>, <a class="ref" href="chord.html#T10" target="_self">Th10</a>, <a class="ref" href="chord.html#T6" target="_self">Th6</a>, <a class="ref" href="glib_000.html#T91">GLIB_000:91</a></i>;<br/>
<b>hence </b><a NAME="E7:50"/>
<font color="Maroon">u2</font>,<font color="Maroon">v2</font> <a href="chord.html#R1" target="_self">are_adjacent</a> 
 <b>by </b><i><a class="ref" href="chord.html#T4" target="_self">Th4</a></i>;<br/>


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