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<b>thus </b><a NAME="E1:13"/>
for <font color="Olive">x</font> being   <a href="hidden.html#M1">set</a>   st <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="xboole_0.html#K1">{}</a>  holds <br/><font color="Olive">x</font> <a href="tarski.html#R1">c=</a>  <a href="xboole_0.html#K1">{}</a> 
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="ordinal1.html#D2" target="_self">ORDINAL1:def 2</a><br/>

<b>thus </b><a NAME="E2:13"/>
for <font color="Olive">x</font>, <font color="Olive">y</font> being   <a href="hidden.html#M1">set</a>   st <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="xboole_0.html#K1">{}</a>  &amp; <font color="Olive">y</font> <a href="hidden.html#R2">in</a>  <a href="xboole_0.html#K1">{}</a>  &amp; not <font color="Olive">x</font> <a href="hidden.html#R2">in</a> <font color="Olive">y</font> &amp; not <font color="Olive">x</font> <a href="hidden.html#R1">=</a> <font color="Olive">y</font> holds <br/><font color="Olive">y</font> <a href="hidden.html#R2">in</a> <font color="Olive">x</font>
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="ordinal1.html#D3" target="_self">ORDINAL1:def 3</a><br/>


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