<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon" title="c2">k</font>, <font color="Maroon" title="c3">k'</font> be    <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of  <a href="numbers.html#K5" title="NUMBERS:func.5">NAT</a> ;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:4_1_2"/><i><font color="Green" title="E3">A3</font></i>: 
 <a href="zf_lang.html#K2" title="ZF_LANG:func.2">x.</a> <font color="Maroon" title="c2">k</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c1">v1</font>
 <b>and </b><br/><a NAME="E2:4_1_2"/><i><font color="Green" title="E4">A4</font></i>: 
 <a href="zf_lang.html#K2" title="ZF_LANG:func.2">x.</a> <font color="Maroon" title="c3">k'</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c1">v1</font>
 ;<br/>

<a NAME="E3:4_1_2"/>
( 5 <a href="nat_1.html#K2" title="NAT_1:func.2">+</a> <font color="Maroon" title="c2">k</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c1">v1</font> &amp; 5 <a href="nat_1.html#K2" title="NAT_1:func.2">+</a> <font color="Maroon" title="c3">k'</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c1">v1</font> )
 
<b>by </b><i><a class="txt" href="zf_fund1.html#E1:4_1_2"><i><font color="Green" title="E3">A3</font></i></a>, <a class="txt" href="zf_fund1.html#E2:4_1_2"><i><font color="Green" title="E4">A4</font></i></a>, <a class="ref" href="zf_lang.html#D2" title="ZF_LANG:def.2">ZF_LANG:def 2</a></i>;<br/>
<b>hence </b><a NAME="E4:4_1_2"/>
<font color="Maroon" title="c2">k</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">k'</font>
 <b>by </b><i><a class="ref" href="xcmplx_1.html#T2" title="XCMPLX_1:th.2">XCMPLX_1:2</a></i>;<br/>


</div>
