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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be   <a href="classes2.html#NM1">Universe</a>;<br/>



<a NAME="E1:54"/>
<font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font> <a href="xboole_0.html#R3">are_c=-comparable</a> 
 
<b>by </b><i><a class="ref" href="classes2.html#T58" target="_self">Th58</a></i>;<br/>
<a NAME="E2:54"/><b>then </b>
( <font color="Maroon">c<sub>1</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>2</sub></font> or <font color="Maroon">c<sub>2</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>1</sub></font> )
 
<b>by </b><i><a class="ref" href="xboole_0.html#D9">XBOOLE_0:def 9</a></i>;<br/>
<b>hence </b><a NAME="E3:54"/>
( <font color="Maroon">c<sub>1</sub></font> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">c<sub>2</sub></font> is   <a href="classes2.html#NM1">Universe</a> &amp; <font color="Maroon">c<sub>1</sub></font> <a href="xboole_0.html#K3">/\</a> <font color="Maroon">c<sub>2</sub></font> is   <a href="classes2.html#NM1">Universe</a> )
 <b>by </b><i><a class="ref" href="xboole_1.html#T12">XBOOLE_1:12</a>, <a class="ref" href="xboole_1.html#T28">XBOOLE_1:28</a></i>;<br/>


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