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<b>let </b><font color="Maroon">I</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">X</font> be    <a href="pboole.html#M1" target="_self">ManySortedSet</a> of <font color="Maroon">I</font>;<br/><b>let </b><font color="Maroon">Y</font> be    <a href="pboole.html#M1" target="_self">ManySortedSet</a> of <font color="Maroon">I</font>;<br/><b>let </b><font color="Maroon">Z</font> be    <a href="pboole.html#M1" target="_self">ManySortedSet</a> of <font color="Maroon">I</font>;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:60"/><i><font color="Green">E24</font></i>: 
<font color="Maroon">X</font> <a href="pboole.html#R2" target="_self">c=</a> <font color="Maroon">Y</font> <a href="pboole.html#K2" target="_self">\/</a> <font color="Maroon">Z</font>
 <b>and </b><br/><a NAME="E2:60"/><i><font color="Green">E25</font></i>: 
<font color="Maroon">X</font> <a href="pboole.html#K3" target="_self">/\</a> <font color="Maroon">Z</font> <a href="pboole.html#R6" target="_self">=</a>  <a href="pboole.html#K1" target="_self">[0]</a> <font color="Maroon">I</font>
 ;<br/>

<a NAME="E3:60"/>
<font color="Maroon">X</font> <a href="pboole.html#K3" target="_self">/\</a> <span class="p1">(<span class="default"><font color="Maroon">Y</font> <a href="pboole.html#K2" target="_self">\/</a> <font color="Maroon">Z</font></span>)</span> <a href="pboole.html#R6" target="_self">=</a> <font color="Maroon">X</font>
 
<b>by </b><i>, </i>;<br/>
<a NAME="E4:60"/><b>then </b>
<span class="p1">(<span class="default"><font color="Maroon">Y</font> <a href="pboole.html#K3" target="_self">/\</a> <font color="Maroon">X</font></span>)</span> <a href="pboole.html#K2" target="_self">\/</a> <span class="p1">(<span class="default"><a href="pboole.html#K1" target="_self">[0]</a> <font color="Maroon">I</font></span>)</span> <a href="pboole.html#R6" target="_self">=</a> <font color="Maroon">X</font>
 
<b>by </b><i>, <a class="ref" href="pboole.html#D3" target="_self">Def3</a></i>;<br/>
<a NAME="E5:60"/><b>then </b>
<font color="Maroon">Y</font> <a href="pboole.html#K3" target="_self">/\</a> <font color="Maroon">X</font> <a href="pboole.html#R6" target="_self">=</a> <font color="Maroon">X</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E6:60"/>
<font color="Maroon">X</font> <a href="pboole.html#R2" target="_self">c=</a> <font color="Maroon">Y</font>
 <b>by </b><i/>;<br/>


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