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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  <a href="facirc_1.html#V1">pair</a>  <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="facirc_1.html#D2">FACIRC_1:def 2</a><br/>

<b>assume </b><a NAME="E1:102_1_1"/>
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K5">NAT</a> 
 ;<br/>

<a NAME="E2:102_1_1"/><b>then </b>
<font color="Maroon">c<sub>1</sub></font> is   <a href="nat_1.html#NM1">Nat</a>
 
;<br/>
<b>hence </b><a NAME="E3:102_1_1"/>
contradiction
 ;<br/>


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