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<b>let </b><font color="Maroon">x1</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">y1</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">x2</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">y2</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<a NAME="E1:139"/><i><font color="Green">E26</font></i>: 
( <font color="Maroon">x2</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">x1</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y1</font> iff ( <font color="Maroon">x2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">x1</font> &amp; <font color="Maroon">y2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">y1</font> ) )
 
<b>by </b><i><a class="ref" href="cohsp_1.html#T20" target="_self">Th20</a></i>;<br/>
<a NAME="E2:139"/>
( <font color="Maroon">x1</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">x2</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y2</font> iff ( <font color="Maroon">x1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">x2</font> &amp; <font color="Maroon">y1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">y2</font> ) )
 
<b>by </b><i><a class="ref" href="cohsp_1.html#T20" target="_self">Th20</a></i>;<br/>
<b>hence </b><a NAME="E3:139"/>
( <font color="Maroon">x1</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x2</font> <a href="cohsp_1.html#K14" target="_self">U+</a> <font color="Maroon">y2</font> iff ( <font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x2</font> &amp; <font color="Maroon">y1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y2</font> ) )
 <b>by </b><i>, <a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>


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