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

<b>let </b><font color="Maroon">Y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">R</font> be    <a href="relset_1.html#M2" target="_self">Relation</a> of <font color="Maroon">X</font>,<font color="Maroon">Y</font>;<br/>





<b>assume </b><a NAME="E1:30"/><i><font color="Green">E20</font></i>: 
 <a href="relat_1.html#K6">id</a> <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">R</font>
 ;<br/>

<b>thus </b><a NAME="E2:30"/>
<font color="Maroon">X</font> <a href="hidden.html#R1">=</a>  <a href="relset_1.html#K4" target="_self">dom</a> <font color="Maroon">R</font>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="30_1"><b>proof </b></a><div class="add">

<a NAME="E1:30_1"/>
<font color="Maroon">X</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K4" target="_self">dom</a> <font color="Maroon">R</font>
 
<b>by </b><i>, </i>;<br/>
<b>hence </b><a NAME="E2:30_1"/>
<font color="Maroon">X</font> <a href="hidden.html#R1">=</a>  <a href="relset_1.html#K4" target="_self">dom</a> <font color="Maroon">R</font>
 <b>by </b><i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>


</div><b>end;</b></div>

<b>thus </b><a NAME="E3:30"/>
<font color="Maroon">X</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K5" target="_self">rng</a> <font color="Maroon">R</font>
 <b>by </b><i>, </i>;<br/>


</div>
