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<b>let </b><font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be  <a href="card_1.html#V1">cardinal</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<b>assume </b><a NAME="E1:3_1_2"/>
( ex <font color="Olive">b<sub>1</sub></font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">c<sub>2</sub></font> st <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="card_1.html#K1">Card</a> <font color="Olive">b<sub>1</sub></font> &amp; ( for <font color="Olive">b<sub>1</sub></font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">c<sub>2</sub></font> holds <font color="Maroon">c<sub>3</sub></font> <a href="card_1.html#NR1" target="_self">&lt;=`</a>  <a href="card_1.html#K1">Card</a> <font color="Olive">b<sub>1</sub></font> ) &amp; ex <font color="Olive">b<sub>1</sub></font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">c<sub>2</sub></font> st <font color="Maroon">c<sub>4</sub></font> <a href="hidden.html#R1">=</a>  <a href="card_1.html#K1">Card</a> <font color="Olive">b<sub>1</sub></font> &amp; ( for <font color="Olive">b<sub>1</sub></font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">c<sub>2</sub></font> holds <font color="Maroon">c<sub>4</sub></font> <a href="card_1.html#NR1" target="_self">&lt;=`</a>  <a href="card_1.html#K1">Card</a> <font color="Olive">b<sub>1</sub></font> ) )
 ;<br/>

<b>hence </b><a NAME="E2:3_1_2"/>
( <font color="Maroon">c<sub>3</sub></font> <a href="ordinal1.html#R1">c=</a> <font color="Maroon">c<sub>4</sub></font> &amp; <font color="Maroon">c<sub>4</sub></font> <a href="ordinal1.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font> )
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a><br/>


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