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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="group_1.html#NM1">Group</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be    <a href="group_2.html#M1" target="_self">Subgroup</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>



<a NAME="E1:88"/><i><font color="Green">E60</font></i>: 
 <a href="group_2.html#K5" target="_self">(1).</a> <font color="Maroon">c<sub>1</sub></font> is    <a href="group_2.html#M1" target="_self">Subgroup</a> of <font color="Maroon">c<sub>2</sub></font>
 
<b>by </b><i><a class="ref" href="group_2.html#T77" target="_self">Th77</a></i>;<br/>
<b>hence </b><a NAME="E2:88"/>
<span class="p1">(<span class="default"><a href="group_2.html#K5" target="_self">(1).</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="group_2.html#K9" target="_self">/\</a> <font color="Maroon">c<sub>2</sub></font> <a href="group_2.html#R1" target="_self">=</a>  <a href="group_2.html#K5" target="_self">(1).</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="group_2.html#E115"><i><font color="Green">Lemma59</font></i></a></i>;<br/>

<b>thus </b><a NAME="E3:88"/>
<font color="Maroon">c<sub>2</sub></font> <a href="group_2.html#K9" target="_self">/\</a> <span class="p1">(<span class="default"><a href="group_2.html#K5" target="_self">(1).</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="group_2.html#R1" target="_self">=</a>  <a href="group_2.html#K5" target="_self">(1).</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="group_2.html#E1:88"><i><font color="Green">E60</font></i></a>, <a class="txt" href="group_2.html#E115"><i><font color="Green">Lemma59</font></i></a></i>;<br/>


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