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<b>let </b><font color="Maroon">G</font> be  <a href="graph_1.html#V3">oriented</a> <a href="graph_1.html#NM1">Graph</a>;<br/><b>let </b><font color="Maroon">v1</font> be   <a href="graph_3.html#NM2">Vertex</a> of <font color="Maroon">G</font>, <font color="Maroon">v2</font> be   <a href="graph_3.html#NM2">Vertex</a> of <font color="Maroon">G</font>;<br/><b>let </b><font color="Maroon">e1</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">e2</font> be    <a href="hidden.html#M1">set</a> ;<br/>





<b>assume </b><a NAME="E1:12"/><i><font color="Green">E34</font></i>: 
( <font color="Maroon">e1</font> <a href="hidden.html#R2">in</a> the <a href="graph_1.html#U2">Edges</a> of <font color="Maroon">G</font> &amp; <font color="Maroon">e2</font> <a href="hidden.html#R2">in</a> the <a href="graph_1.html#U2">Edges</a> of <font color="Maroon">G</font> &amp; <font color="Maroon">e1</font> <a href="graph_4.html#R1">orientedly_joins</a> <font color="Maroon">v1</font>,<font color="Maroon">v2</font> &amp; <font color="Maroon">e2</font> <a href="graph_4.html#R1">orientedly_joins</a> <font color="Maroon">v1</font>,<font color="Maroon">v2</font> )
 ;<br/>

<a NAME="E2:12"/><b>then </b>
( the <a href="graph_1.html#U3">Source</a> of <font color="Maroon">G</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">e1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v1</font> &amp; the <a href="graph_1.html#U4">Target</a> of <font color="Maroon">G</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">e1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v2</font> &amp; the <a href="graph_1.html#U3">Source</a> of <font color="Maroon">G</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">e2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v1</font> &amp; the <a href="graph_1.html#U4">Target</a> of <font color="Maroon">G</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">e2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v2</font> )
 
<b>by </b><i><a class="ref" href="graph_4.html#D1">GRAPH_4:def 1</a></i>;<br/>
<b>hence </b><a NAME="E3:12"/>
<font color="Maroon">e1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">e2</font>
 <b>by </b><i>, <a class="ref" href="graph_1.html#D4">GRAPH_1:def 4</a></i>;<br/>


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