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<a NAME="E1:42_1_1"/>
 <a href="ordinal1.html#K3">On</a> <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="classes2.html#T55">CLASSES2:55</a></i>;<br/>
<a NAME="E2:42_1_1"/><b>then </b>
(  <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R2">in</a>  <a href="ordinal1.html#K3">On</a> <font color="Maroon">c<sub>1</sub></font> &amp;  <a href="ordinal1.html#K3">On</a> <font color="Maroon">c<sub>1</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="ordinal2.html#T9">ORDINAL2:9</a>, <a class="ref" href="ordinal3.html#T10">ORDINAL3:10</a></i>;<br/>
<a NAME="E3:42_1_1"/><b>then </b>
1 <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="ref" href="classes2.html#T6">CLASSES2:6</a>, <a class="txt" href="ordinal4.html#E1"><i><font color="Green">Lemma1</font></i></a></i>;<br/>
<a NAME="E4:42_1_1"/><b>then </b>
( not 1 is <a href="xboole_0.html#V1">empty</a> &amp; 1 is    <a href="ordinal4.html#M1" target="_self">Ordinal</a> of <font color="Maroon">c<sub>1</sub></font> )
 
<b>by </b><i><a class="ref" href="ordinal4.html#D2" target="_self">Def2</a></i>;<br/>
<b>hence </b><a NAME="E5:42_1_1"/>
not for <font color="Olive">b<sub>1</sub></font> being   <a href="ordinal4.html#M1" target="_self">Ordinal</a> of <font color="Maroon">c<sub>1</sub></font> holds <font color="Olive">b<sub>1</sub></font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/>


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