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<b>let </b><font color="Maroon" title="c4">x</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="valued_0.html#D12" title="VALUED_0:def.12">VALUED_0:def 12</a><br/>

<b>assume </b><a NAME="E1:28_1_1"/>
<font color="Maroon" title="c4">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="relat_1.html#NK2" title="RELAT_1:NK.2">dom</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="nat_3.html#K4" title="NAT_3:func.4">*</a> <font color="Maroon" title="c2">b</font></span>)</span>
 ;<br/>

<a NAME="E2:28_1_1"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="nat_3.html#K4" title="NAT_3:func.4">*</a> <font color="Maroon" title="c2">b</font></span>)</span> <a href="seq_1.html#K1" title="SEQ_1:func.1">.</a> <font color="Maroon" title="c4">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">a</font> <a href="xcmplx_0.html#K3" title="XCMPLX_0:func.3">*</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">b</font> <a href="seq_1.html#K1" title="SEQ_1:func.1">.</a> <font color="Maroon" title="c4">x</font></span>)</span>
 
<b>by </b><i><a class="ref" href="nat_3.html#D2" target="_self" title="NAT_3:def.2">Def2</a></i>;<br/>
<b>hence </b><a NAME="E3:28_1_1"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="nat_3.html#K4" title="NAT_3:func.4">*</a> <font color="Maroon" title="c2">b</font></span>)</span> <a href="funct_1.html#K1" title="FUNCT_1:func.1">.</a> <font color="Maroon" title="c4">x</font> is <a href="ordinal1.html#V7" title="ORDINAL1:attr.7">natural</a>
 ;<br/>


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