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<b>let </b><font color="Maroon">i</font> be   <a href="nat_1.html#NM1">Nat</a>;<br/><b>let </b><font color="Maroon">j</font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>



<b>assume </b><a NAME="E1:13"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">i</font> <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">j</font> <a href="hidden.html#R1">=</a> 0
 ;<br/>

<a NAME="E2:13"/>
( 0 <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">i</font> &amp; 0 <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">j</font> )
 
<b>by </b><i/>;<br/>
<a NAME="E3:13"/><b>then </b>
( 0 <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">i</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">j</font> <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">i</font> &amp; 0 <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">j</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">i</font> <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">j</font> &amp; 0 <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">i</font> <a href="hidden.html#R1">=</a> <font color="Maroon">i</font> &amp; 0 <a href="xcmplx_0.html#K2">+</a> <font color="Maroon">j</font> <a href="hidden.html#R1">=</a> <font color="Maroon">j</font> )
 
<b>by </b><i><a class="ref" href="xreal_1.html#T9">XREAL_1:9</a></i>;<br/>
<b>hence </b><a NAME="E4:13"/>
( <font color="Maroon">i</font> <a href="hidden.html#R1">=</a> 0 &amp; <font color="Maroon">j</font> <a href="hidden.html#R1">=</a> 0 )
 <b>by </b><i>, </i>;<br/>


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