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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="glib_000.html#NM2">_Graph</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be    <a href="hidden.html#M1">set</a> ;<br/>



<b>consider </b><font color="Maroon">c<sub>3</sub></font> being   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>
<b>assume </b><a NAME="E2:82"/>
<font color="Maroon">c<sub>1</sub></font> <a href="glib_002.html#R1" target="_self">is_DTree_rooted_at</a> <font color="Maroon">c<sub>2</sub></font>
 ;<br/>

<b>then consider </b><font color="Maroon">c<sub>4</sub></font> being   <a href="glib_001.html#NM6">DWalk</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E4:82"/><i><font color="Green">E49</font></i>: 
<font color="Maroon">c<sub>4</sub></font> <a href="glib_001.html#R1">is_Walk_from</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="glib_002.html#D4" target="_self">Def4</a></i>;<br/>
<b>thus </b><a NAME="E5:82"/>
<font color="Maroon">c<sub>2</sub></font> is   <a href="glib_000.html#NM10">Vertex</a> of <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="glib_002.html#E4:82"><i><font color="Green">E49</font></i></a>, <a class="ref" href="glib_001.html#T19">GLIB_001:19</a></i>;<br/>


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