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<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<a NAME="E1:14"/>
( <font color="Maroon">x</font> is   <a href="rat_1.html#NM1">Rational</a> iff <font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K3">RAT</a>  )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E2:14"/>
(  ex <font color="Olive">m</font>, <font color="Olive">n</font> being  <a href="int_1.html#NM1">Integer</a> st <font color="Maroon">x</font> <a href="hidden.html#R1">=</a> <font color="Olive">m</font> <a href="xcmplx_0.html#K7">/</a> <font color="Olive">n</font> implies <font color="Maroon">x</font> is <a href="rat_1.html#V1" target="_self">rational</a> )
 <b>by </b><i/>;<br/>


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