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<b>let </b><font color="Maroon">G</font> be   <a href="glib_003.html#NM3">VGraph</a>;<br/><b>let </b><font color="Maroon">e</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/>



<b>assume </b><a NAME="E1:195"/>
<font color="Maroon">e</font> <a href="hidden.html#R2">in</a>  <a href="glib_000.html#K6">the_Vertices_of</a> <font color="Maroon">G</font>
 ;<br/>

<a NAME="E2:195"/><b>then </b>
<span class="p1">(<span class="default"><font color="Maroon">G</font> <a href="glib_003.html#K13" target="_self">.labelVertex</a> <font color="Maroon">e</font>,<font color="Maroon">x</font></span>)</span> <a href="glib_003.html#K14" target="_self">.labeledV()</a>  <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">G</font> <a href="glib_003.html#K14" target="_self">.labeledV()</a> </span>)</span> <a href="xboole_0.html#K2">\/</a> <span class="p1"><a href="tarski.html#K1">{</a><span class="default"><font color="Maroon">e</font></span><a href="tarski.html#K1">}</a></span>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E3:195"/>
<font color="Maroon">G</font> <a href="glib_003.html#K14" target="_self">.labeledV()</a>  <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">G</font> <a href="glib_003.html#K13" target="_self">.labelVertex</a> <font color="Maroon">e</font>,<font color="Maroon">x</font></span>)</span> <a href="glib_003.html#K14" target="_self">.labeledV()</a> 
 <b>by </b><i><a class="ref" href="xboole_1.html#T7">XBOOLE_1:7</a></i>;<br/>


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