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<b>let </b><font color="Maroon">i</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">j</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a> ;<br/>



<b>assume </b><a NAME="E1:31"/>
( <font color="Maroon">i</font> is <a href="abian.html#V1">even</a> &amp; <font color="Maroon">j</font> is <a href="abian.html#V1">even</a> )
 ;<br/>

<b>then reconsider </b><font color="Maroon">i'</font> = <font color="Maroon">i</font>, <font color="Maroon">j'</font> = <font color="Maroon">j</font> as  <a href="abian.html#V1">even</a>  <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a>  ;<br/>
<a NAME="E3:31"/>
<font color="Maroon">i'</font> <a href="nat_1.html#K2">*</a> <font color="Maroon">j'</font> is <a href="abian.html#V1">even</a>
 
;<br/>
<b>hence </b><a NAME="E4:31"/>
<font color="Maroon">i</font> <a href="nat_1.html#K2">*</a> <font color="Maroon">j</font> is <a href="abian.html#V1">even</a>
 ;<br/>


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