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<b>let </b><font color="Maroon">p</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="qc_lang1.html#K8">QC-WFF</a> ;<br/><b>let </b><font color="Maroon">q</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="qc_lang1.html#K8">QC-WFF</a> ;<br/><b>let </b><font color="Maroon">V</font> be  non <a href="xboole_0.html#V1">empty</a> <a href="subset_1.html#NM2">Subset</a> of <a href="qc_lang1.html#K1">QC-variables</a> ;<br/>





<b>set </b><font color="Maroon">pq</font> = <font color="Maroon">p</font> <a href="qc_lang1.html#K13">'&amp;'</a> <font color="Maroon">q</font>;<br/>
<a NAME="E1:49"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">p</font> <a href="qc_lang1.html#K13">'&amp;'</a> <font color="Maroon">q</font> is <a href="qc_lang1.html#V4">conjunctive</a>
 
<b>by </b><i><a class="ref" href="qc_lang1.html#D19">QC_LANG1:def 19</a></i>;<br/>
<a NAME="E2:49"/><b>then </b>
(  <a href="qc_lang1.html#K18">the_left_argument_of</a> <span class="p1">(<span class="default"><font color="Maroon">p</font> <a href="qc_lang1.html#K13">'&amp;'</a> <font color="Maroon">q</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">p</font> &amp;  <a href="qc_lang1.html#K19">the_right_argument_of</a> <span class="p1">(<span class="default"><font color="Maroon">p</font> <a href="qc_lang1.html#K13">'&amp;'</a> <font color="Maroon">q</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">q</font> )
 
<b>by </b><i><a class="ref" href="qc_lang1.html#D24">QC_LANG1:def 24</a>, <a class="ref" href="qc_lang1.html#D25">QC_LANG1:def 25</a></i>;<br/>
<b>hence </b><a NAME="E3:49"/>
 <a href="qc_lang3.html#K4" target="_self">Vars</a> <span class="p1">(<span class="default"><font color="Maroon">p</font> <a href="qc_lang1.html#K13">'&amp;'</a> <font color="Maroon">q</font></span>)</span>,<font color="Maroon">V</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="qc_lang3.html#K4" target="_self">Vars</a> <font color="Maroon">p</font>,<font color="Maroon">V</font></span>)</span> <a href="subset_1.html#K4">\/</a> <span class="p1">(<span class="default"><a href="qc_lang3.html#K4" target="_self">Vars</a> <font color="Maroon">q</font>,<font color="Maroon">V</font></span>)</span>
 <b>by </b><i>, </i>;<br/>


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