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<b>let </b><font color="Maroon">x1</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x2</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x3</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x4</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x5</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x6</font> be    <a href="hidden.html#M1">set</a> ;<br/>











<b>assume </b><a NAME="E1:7"/><i><font color="Green">E34</font></i>: 
<span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="enumset1.html#K1">}</a></span> <a href="subset_1.html#R1">misses</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x4</font>,<font color="Maroon">x5</font>,<font color="Maroon">x6</font></span><a href="enumset1.html#K1">}</a></span>
 ;<br/>

<b>assume </b><a NAME="E2:7"/>
( <font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x4</font> or <font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x5</font> or <font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x6</font> or <font color="Maroon">x2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x4</font> or <font color="Maroon">x2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x5</font> or <font color="Maroon">x2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x6</font> or <font color="Maroon">x3</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x4</font> or <font color="Maroon">x3</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x5</font> or <font color="Maroon">x3</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x6</font> )
 ;<br/>

<a NAME="E3:7"/><b>then </b><i><font color="Green">E35</font></i>: 
( <font color="Maroon">x4</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="enumset1.html#K1">}</a></span> or <font color="Maroon">x5</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="enumset1.html#K1">}</a></span> or <font color="Maroon">x6</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="enumset1.html#K1">}</a></span> )
 
<b>by </b><i><a class="ref" href="enumset1.html#D1">ENUMSET1:def 1</a></i>;<br/>
<a NAME="E4:7"/>
( <font color="Maroon">x4</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x4</font>,<font color="Maroon">x5</font>,<font color="Maroon">x6</font></span><a href="enumset1.html#K1">}</a></span> &amp; <font color="Maroon">x5</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x4</font>,<font color="Maroon">x5</font>,<font color="Maroon">x6</font></span><a href="enumset1.html#K1">}</a></span> &amp; <font color="Maroon">x6</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="enumset1.html#K1">{</a><span class="default"><font color="Maroon">x4</font>,<font color="Maroon">x5</font>,<font color="Maroon">x6</font></span><a href="enumset1.html#K1">}</a></span> )
 
<b>by </b><i><a class="ref" href="enumset1.html#D1">ENUMSET1:def 1</a></i>;<br/>
<b>hence </b><a NAME="E5:7"/>
contradiction
 <b>by </b><i>, , <a class="ref" href="xboole_0.html#T3">XBOOLE_0:3</a></i>;<br/>


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