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<b>let </b><font color="Maroon">D</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">d1</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font>;<br/><b>let </b><font color="Maroon">d2</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font>;<br/>





<b>set </b><font color="Maroon">s</font> = <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span>;<br/>
<a NAME="E1:24"/>
(  <a href="finseq_1.html#K4">dom</a> <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K2">{</a><span class="default">1,2</span><a href="tarski.html#K2">}</a></span> &amp; <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span> <a href="funct_1.html#K1">.</a> 1 <a href="hidden.html#R1">=</a> <font color="Maroon">d1</font> &amp; <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a> <font color="Maroon">d2</font> &amp; 1 <a href="hidden.html#R2">in</a> <span class="p1"><a href="tarski.html#K2">{</a><span class="default">1,2</span><a href="tarski.html#K2">}</a></span> &amp; 2 <a href="hidden.html#R2">in</a> <span class="p1"><a href="tarski.html#K2">{</a><span class="default">1,2</span><a href="tarski.html#K2">}</a></span> )
 
<b>by </b><i><a class="ref" href="finseq_1.html#T4">FINSEQ_1:4</a>, <a class="ref" href="finseq_1.html#T61">FINSEQ_1:61</a>, <a class="ref" href="finseq_3.html#T29">FINSEQ_3:29</a></i>;<br/>
<b>hence </b><a NAME="E2:24"/>
( <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span> <a href="finseq_4.html#K4" target="_self">/.</a> 1 <a href="hidden.html#R1">=</a> <font color="Maroon">d1</font> &amp; <span class="p1"><a href="finseq_4.html#K2" target="_self">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2" target="_self">*&gt;</a></span> <a href="finseq_4.html#K4" target="_self">/.</a> 2 <a href="hidden.html#R1">=</a> <font color="Maroon">d2</font> )
 <b>by </b><i/>;<br/>


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