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<b>let </b><font color="Maroon">c<sub>1</sub></font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be    <a href="pboole.html#M1" target="_self">ManySortedSet</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>







<b>assume </b><a NAME="E1:45"/>
<span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="pboole.html#K2" target="_self">\/</a> <font color="Maroon">c<sub>3</sub></font></span>)</span> <a href="pboole.html#K3" target="_self">/\</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="pboole.html#K2" target="_self">\/</a> <font color="Maroon">c<sub>4</sub></font></span>)</span> <a href="pboole.html#R6" target="_self">=</a> <font color="Maroon">c<sub>2</sub></font>
 ;<br/>

<a NAME="E2:45"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font> <a href="pboole.html#R6" target="_self">=</a> <font color="Maroon">c<sub>2</sub></font> <a href="pboole.html#K2" target="_self">\/</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="pboole.html#K3" target="_self">/\</a> <font color="Maroon">c<sub>4</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="pboole.html#T39" target="_self">Th39</a></i>;<br/>
<b>hence </b><a NAME="E3:45"/>
<font color="Maroon">c<sub>3</sub></font> <a href="pboole.html#K3" target="_self">/\</a> <font color="Maroon">c<sub>4</sub></font> <a href="pboole.html#R2" target="_self">c=</a> <font color="Maroon">c<sub>2</sub></font>
 <b>by </b><i><a class="ref" href="pboole.html#T16" target="_self">Th16</a></i>;<br/>


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