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<b>let </b><font color="Maroon" title="c1">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="membered.html#D6" target="_self" title="MEMBERED:def.6">MEMBERED:def 6</a><br/>

<b>thus </b><a NAME="E1:36_1_1"/>
( <font color="Maroon" title="c1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a>  implies <font color="Maroon" title="c1">x</font> is <a href="ordinal1.html#V7" title="ORDINAL1:attr.7">natural</a> )
 ;<br/>


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