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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">O</font> be   <a href="orders_1.html#NM2">Order</a> of <font color="Maroon">X</font>;<br/>



<b>thus </b><font color="Maroon">X</font> = 
<font color="Maroon">X</font> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">X</font>

<br/>.= 
<span class="p1">(<span class="default"><a href="relset_1.html#K4">dom</a> <font color="Maroon">O</font></span>)</span> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">X</font>
<b>by </b><i/>
<br/>.= 
 <a href="relat_1.html#K3">field</a> <font color="Maroon">O</font>
<b>by </b><i/>
;<br/>


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