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



<a NAME="E1:9"/>
( <font color="Maroon">M</font> <a href="xboole_0.html#R2">c&lt;</a> <font color="Maroon">N</font> iff ( <font color="Maroon">M</font> <a href="ordinal1.html#R1">c=</a> <font color="Maroon">N</font> &amp; <font color="Maroon">M</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">N</font> ) )
 
<b>by </b><i><a class="ref" href="xboole_0.html#D8">XBOOLE_0:def 8</a></i>;<br/>
<b>hence </b><a NAME="E2:9"/>
( <font color="Maroon">M</font> <a href="card_1.html#NR2" target="_self">&lt;`</a> <font color="Maroon">N</font> iff ( <font color="Maroon">M</font> <a href="card_1.html#NR1" target="_self">&lt;=`</a> <font color="Maroon">N</font> &amp; <font color="Maroon">M</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">N</font> ) )
 <b>by </b><i><a class="ref" href="ordinal1.html#T21">ORDINAL1:21</a>, <a class="ref" href="ordinal1.html#D2">ORDINAL1:def 2</a></i>;<br/>


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