<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">G</font> be   <a href="group_1.html#NM1">Group</a>;<br/><b>let </b><font color="Maroon">N1</font> be  <a href="group_3.html#V1">normal</a>  <a href="group_2.html#M1">Subgroup</a> of <font color="Maroon">G</font>;<br/><b>let </b><font color="Maroon">N2</font> be  <a href="group_3.html#V1">normal</a>  <a href="group_2.html#M1">Subgroup</a> of <font color="Maroon">G</font>;<br/>





<a NAME="E1:75"/>
( <span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N1</font>,<font color="Maroon">N2</font></span><a href="group_5.html#K8" target="_self">.]</a></span> is    <a href="group_2.html#M1">Subgroup</a> of <span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N2</font>,<font color="Maroon">N1</font></span><a href="group_5.html#K8" target="_self">.]</a></span> &amp; <span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N2</font>,<font color="Maroon">N1</font></span><a href="group_5.html#K8" target="_self">.]</a></span> is    <a href="group_2.html#M1">Subgroup</a> of <span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N1</font>,<font color="Maroon">N2</font></span><a href="group_5.html#K8" target="_self">.]</a></span> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E2:75"/>
<span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N1</font>,<font color="Maroon">N2</font></span><a href="group_5.html#K8" target="_self">.]</a></span> <a href="group_2.html#R1">=</a> <span class="p1"><a href="group_5.html#K8" target="_self">[.</a><span class="default"><font color="Maroon">N2</font>,<font color="Maroon">N1</font></span><a href="group_5.html#K8" target="_self">.]</a></span>
 <b>by </b><i><a class="ref" href="group_2.html#T64">GROUP_2:64</a></i>;<br/>


</div>
