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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be    <a href="subset_1.html#M1">Element</a> of  <a href="substut1.html#K16" target="_self">QC-Sub-WFF</a> ;<br/>



<b>assume </b><a NAME="E1:85"/><i><font color="Green">E51</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="substut1.html#K19" target="_self">`2</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>2</sub></font> <a href="substut1.html#K19" target="_self">`2</a> 
 ;<br/>

<b>set </b><font color="Maroon">c<sub>3</sub></font> =  <a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>;<br/>
<a NAME="E2:85"/><i><font color="Green">E52</font></i>: 
 <a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font> is <a href="substut1.html#V6" target="_self">Sub_conjunctive</a>
 
<b>by </b><i><a class="txt" href="substut1.html#E1:85"><i><font color="Green">E51</font></i></a>, <a class="ref" href="substut1.html#T13" target="_self">Th13</a></i>;<br/>
<a NAME="E3:85"/>
(  <a href="substut1.html#K28" target="_self">Sub_the_left_argument_of</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>1</sub></font> &amp;  <a href="substut1.html#K29" target="_self">Sub_the_right_argument_of</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>2</sub></font> )
 
<b>by </b><i><a class="txt" href="substut1.html#E1:85"><i><font color="Green">E51</font></i></a>, <a class="ref" href="substut1.html#T18" target="_self">Th18</a>, <a class="ref" href="substut1.html#T19" target="_self">Th19</a></i>;<br/>
<b>hence </b><a NAME="E4:85"/>
 <a href="substut1.html#K37" target="_self">CQC_Sub</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="qc_lang1.html#K13">'&amp;'</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">c<sub>2</sub></font></span>)</span>
 <b>by </b><i><a class="txt" href="substut1.html#E2:85"><i><font color="Green">E52</font></i></a>, <a class="ref" href="substut1.html#T30" target="_self">Th30</a></i>;<br/>


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