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<b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">Y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">P</font> be   <a href="relat_1.html#NM1">Relation</a>;<br/><b>let </b><font color="Maroon">R</font> be   <a href="relat_1.html#NM1">Relation</a>;<br/>







<b>assume </b><a NAME="E1:170"/>
( <font color="Maroon">P</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">R</font> &amp; <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font> )
 ;<br/>

<a NAME="E2:170"/><b>then </b>
( <font color="Maroon">P</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">R</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">X</font> &amp; <font color="Maroon">R</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">R</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">Y</font> )
 
<b>by </b><i><a class="ref" href="relat_1.html#T62" target="_self">Th62</a>, <a class="ref" href="relat_1.html#T64" target="_self">Th64</a></i>;<br/>
<b>hence </b><a NAME="E3:170"/>
<font color="Maroon">P</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">R</font> <a href="relat_1.html#K10" target="_self">"</a> <font color="Maroon">Y</font>
 <b>by </b><i><a class="ref" href="xboole_1.html#T1">XBOOLE_1:1</a></i>;<br/>


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