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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <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="subset_1.html#NM2">Subset</a> of <a href="cqc_lang.html#K7">CQC-WFF</a> ;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:29"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="cqc_the3.html#R4" target="_self">|-|</a> <font color="Maroon">c<sub>2</sub></font>
 <b>and </b><br/><a NAME="E2:29"/><i><font color="Green">E27</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<a NAME="E3:29"/>
<font color="Maroon">c<sub>1</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font> <a href="cqc_the3.html#R4" target="_self">|-|</a> <font color="Maroon">c<sub>2</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font>
 
<b>by </b><i><a class="txt" href="cqc_the3.html#E1:29"><i><font color="Green">E26</font></i></a>, <a class="ref" href="cqc_the3.html#T25" target="_self">Th25</a></i>;<br/>
<a NAME="E4:29"/><b>then </b>
 <a href="cqc_the1.html#K1">Cn</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="cqc_the1.html#K1">Cn</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="cqc_the3.html#T20" target="_self">Th20</a></i>;<br/>
<a NAME="E5:29"/><b>then </b>
<font color="Maroon">c<sub>4</sub></font> <a href="tarski.html#R1">c=</a>  <a href="cqc_the1.html#K1">Cn</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font></span>)</span>
 
<b>by </b><i><a class="txt" href="cqc_the3.html#E2:29"><i><font color="Green">E27</font></i></a>, <a class="ref" href="cqc_the3.html#T7" target="_self">Th7</a></i>;<br/>
<b>hence </b><a NAME="E6:29"/>
<font color="Maroon">c<sub>2</sub></font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">c<sub>3</sub></font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="ref" href="cqc_the3.html#T7" target="_self">Th7</a></i>;<br/>


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