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<b>let </b><font color="Maroon" title="c3">a</font> be  <a href="facirc_1.html#V1" title="FACIRC_1:attr.1">pair</a>  <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="facirc_1.html#D2" target="_self" title="FACIRC_1:def.2">FACIRC_1:def 2</a><br/>

<b>assume </b><a NAME="E1:11_1_1"/>
<font color="Maroon" title="c3">a</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c1">X</font> <a href="subset_1.html#K6" title="SUBSET_1:func.6">\</a> <font color="Maroon" title="c2">Y</font>
 ;<br/>

<b>hence </b><a NAME="E2:11_1_1"/>
contradiction
 <b>by </b><i><a class="ref" href="facirc_1.html#D2" target="_self" title="FACIRC_1:def.2">Def2</a></i>;<br/>


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