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<b>let </b><font color="Maroon">K1</font> be   <a href="card_1.html#NM1">Cardinal</a>, <font color="Maroon">K2</font> be   <a href="card_1.html#NM1">Cardinal</a>;<br/>

<b>assume </b><a NAME="E1:22_2_2"/>
( <font color="Maroon">M</font> <a href="zfrefle1.html#R4">is_cofinal_with</a> <font color="Maroon">K1</font> &amp; ( for <font color="Olive">N</font> being  <a href="card_1.html#NM1">Cardinal</a>  st <font color="Maroon">M</font> <a href="zfrefle1.html#R4">is_cofinal_with</a> <font color="Olive">N</font> holds <br/><font color="Maroon">K1</font> <a href="card_1.html#NR1" target="_self">&lt;=`</a> <font color="Olive">N</font> ) &amp; <font color="Maroon">M</font> <a href="zfrefle1.html#R4">is_cofinal_with</a> <font color="Maroon">K2</font> &amp; ( for <font color="Olive">N</font> being  <a href="card_1.html#NM1">Cardinal</a>  st <font color="Maroon">M</font> <a href="zfrefle1.html#R4">is_cofinal_with</a> <font color="Olive">N</font> holds <br/><font color="Maroon">K2</font> <a href="card_1.html#NR1" target="_self">&lt;=`</a> <font color="Olive">N</font> ) )
 ;<br/>

<a NAME="E2:22_2_2"/><b>then </b>
( <font color="Maroon">K1</font> <a href="card_1.html#NR1" target="_self">&lt;=`</a> <font color="Maroon">K2</font> &amp; <font color="Maroon">K2</font> <a href="card_1.html#NR1" target="_self">&lt;=`</a> <font color="Maroon">K1</font> )
 
;<br/>
<b>hence </b><a NAME="E3:22_2_2"/>
<font color="Maroon">K1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">K2</font>
 <b>by </b><i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>


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