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<b>let </b><font color="Maroon">A</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<b>assume </b><a NAME="E1:5_1_1"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">A</font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/>

<b>take </b>
 <a href="xboole_0.html#K1">{}</a> 
; <i><font color="Red">:: according to </font></i><a class="ref" href="finset_1.html#D1" target="_self">FINSET_1:def 1</a><br/>

<b>thus </b><a NAME="E2:5_1_1"/>
 <a href="relat_1.html#K2">rng</a> <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">A</font>
 <b>by </b><i/>;<br/>

<b>thus </b><a NAME="E3:5_1_1"/>
 <a href="relat_1.html#K1">dom</a> <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R2">in</a>  <a href="ordinal1.html#K5">omega</a> 
 <b>by </b><i><a class="ref" href="ordinal1.html#D12">ORDINAL1:def 12</a></i>;<br/>


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