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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="zf_lang.html#NM1">Variable</a>;<br/>

<b>assume </b><a NAME="E1:130"/><i><font color="Green">E41</font></i>: 
( <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 0 or <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 1 or <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 2 or <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 3 or <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 4 )
 ;<br/>

<a NAME="E2:130"/>
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R2">in</a>  <a href="zf_lang.html#K1">VAR</a> 
 
;<br/>
<a NAME="E3:130"/><b>then </b>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="nat_1.html#NM1">Nat</a> st <br/>( <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <font color="Olive">b<sub>1</sub></font> &amp; 5 <a href="xxreal_0.html#R1">&lt;=</a> <font color="Olive">b<sub>1</sub></font> )
 
<b>by </b><i><a class="ref" href="zf_lang.html#D1">ZF_LANG:def 1</a></i>;<br/>
<b>hence </b><a NAME="E4:130"/>
contradiction
 <b>by </b><i><a class="txt" href="zf_lang1.html#E1:130"><i><font color="Green">E41</font></i></a></i>;<br/>


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