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<b>assume </b><a NAME="E1:63"/>
 <a href="kurato_1.html#K6" title="KURATO_1:func.6">KurExSet</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <a href="kurato_1.html#K6" title="KURATO_1:func.6">KurExSet</a>  <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
 ;<br/>

<a NAME="E2:63"/><b>then </b>
 <a href="kurato_1.html#K6" title="KURATO_1:func.6">KurExSet</a>  <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <a href="kurato_1.html#K6" title="KURATO_1:func.6">KurExSet</a>  <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
 
<b>by </b><i><a class="ref" href="xboole_1.html#T66" title="XBOOLE_1:th.66">XBOOLE_1:66</a></i>;<br/>
<b>hence </b><a NAME="E3:63"/>
contradiction
 <b>by </b><i><a class="ref" href="xboole_1.html#T79" title="XBOOLE_1:th.79">XBOOLE_1:79</a></i>;<br/>


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