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

<b>let </b><font color="Maroon">Y</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">PA</font> be    <a href="eqrel_1.html#M1">a_partition</a> of <font color="Maroon">Y</font>, <font color="Maroon">PB</font> be    <a href="eqrel_1.html#M1">a_partition</a> of <font color="Maroon">Y</font>;<br/>



<a NAME="E1:38"/><i><font color="Green">E42</font></i>: 
 <a href="partit1.html#K4" target="_self">ERl</a> <span class="p1">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K3" target="_self">'\/'</a> <span class="p2">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K2" target="_self">'/\'</a> <font color="Maroon">PB</font></span>)</span></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PA</font></span>)</span> <a href="eqrel_1.html#K5">"\/"</a> <span class="p1">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <span class="p2">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K2" target="_self">'/\'</a> <font color="Maroon">PB</font></span>)</span></span>)</span>
 
<b>by </b><i/>;<br/>
<a NAME="E2:38"/>
<span class="p1">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PA</font></span>)</span> <a href="eqrel_1.html#K5">"\/"</a> <span class="p1">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <span class="p2">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K2" target="_self">'/\'</a> <font color="Maroon">PB</font></span>)</span></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PA</font></span>)</span> <a href="eqrel_1.html#K5">"\/"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PA</font></span>)</span> <a href="eqrel_1.html#K4">/\</a> <span class="p2">(<span class="default"><a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PB</font></span>)</span></span>)</span>
 
<b>by </b><i/>;<br/>
<a NAME="E3:38"/><b>then </b>
 <a href="partit1.html#K4" target="_self">ERl</a> <span class="p1">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K3" target="_self">'\/'</a> <span class="p2">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K2" target="_self">'/\'</a> <font color="Maroon">PB</font></span>)</span></span>)</span> <a href="hidden.html#R1">=</a>  <a href="partit1.html#K4" target="_self">ERl</a> <font color="Maroon">PA</font>
 
<b>by </b><i>, <a class="ref" href="eqrel_1.html#T25">EQREL_1:25</a></i>;<br/>
<b>hence </b><a NAME="E4:38"/>
<font color="Maroon">PA</font> <a href="partit1.html#K3" target="_self">'\/'</a> <span class="p1">(<span class="default"><font color="Maroon">PA</font> <a href="partit1.html#K2" target="_self">'/\'</a> <font color="Maroon">PB</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">PA</font>
 <b>by </b><i/>;<br/>


</div>
