<?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">H1</font> be    <a href="group_2.html#M1">Subgroup</a> of <font color="Maroon">G</font>, <font color="Maroon">H2</font> be    <a href="group_2.html#M1">Subgroup</a> of <font color="Maroon">G</font>;<br/><b>let </b><font color="Maroon">A</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">G</font>;<br/>





<b>assume </b><a NAME="E1:4"/><i><font color="Green">E23</font></i>: 
<font color="Maroon">A</font> <a href="hidden.html#R1">=</a> the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">H1</font> <a href="xboole_0.html#K2">\/</a> the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">H2</font>
 ;<br/>

<a NAME="E2:4"/>
the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">H2</font> <a href="hidden.html#R1">=</a>  <a href="group_2.html#K7">carr</a> <font color="Maroon">H2</font>
 
<b>by </b><i><a class="ref" href="group_2.html#D9">GROUP_2:def 9</a></i>;<br/>
<a NAME="E3:4"/><b>then </b>
<font color="Maroon">A</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="group_2.html#K7">carr</a> <font color="Maroon">H1</font></span>)</span> <a href="subset_1.html#K4">\/</a> <span class="p1">(<span class="default"><a href="group_2.html#K7">carr</a> <font color="Maroon">H2</font></span>)</span>
 
<b>by </b><i>, <a class="ref" href="group_2.html#D9">GROUP_2:def 9</a></i>;<br/>
<b>hence </b><a NAME="E4:4"/>
<font color="Maroon">H1</font> <a href="group_4.html#K8">"\/"</a> <font color="Maroon">H2</font> <a href="group_2.html#R1">=</a>  <a href="group_4.html#K5">gr</a> <font color="Maroon">A</font>
 <b>by </b><i><a class="ref" href="group_4.html#D10">GROUP_4:def 10</a></i>;<br/>


</div>
