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<b>let </b><font color="Maroon" title="c1">p</font>, <font color="Maroon" title="c2">q</font> be    <a href="subset_1.html#M2" title="SUBSET_1:mode.2">Element</a> of  <a href="cqc_lang.html#K7" title="CQC_LANG:func.7">CQC-WFF</a> ;<br/><b>let </b><font color="Maroon" title="c3">x</font> be   <a href="qc_lang1.html#NM3" title="QC_LANG1:NM.3">bound_QC-variable</a>;<br/>





<b>assume </b><a NAME="E1:87"/><i><font color="Green" title="E59">A1</font></i>: 
not <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="qc_lang1.html#K23" title="QC_LANG1:func.23">still_not-bound_in</a> <font color="Maroon" title="c1">p</font>
 ;<br/>

<a NAME="E2:87"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 
<b>by </b><i><a class="ref" href="cqc_the2.html#T18" target="_self" title="CQC_THE2:th.18">Th18</a></i>;<br/>
<a NAME="E3:87"/><b>then </b><i><font color="Green" title="E60">A2</font></i>: 
<font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p3">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 
<b>by </b><i><a class="ref" href="cqc_the2.html#T4" target="_self" title="CQC_THE2:th.4">Th4</a></i>;<br/>
<a NAME="E4:87"/>
not <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="qc_lang1.html#K23" title="QC_LANG1:func.23">still_not-bound_in</a> <span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span>
 
<b>by </b><i><a class="ref" href="cqc_the2.html#T6" target="_self" title="CQC_THE2:th.6">Th6</a></i>;<br/>
<a NAME="E5:87"/><b>then </b>
not <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="qc_lang1.html#K23" title="QC_LANG1:func.23">still_not-bound_in</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p3">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span></span>)</span>
 
<b>by </b><i><a class="txt" href="cqc_the2.html#E1:87"><i><font color="Green" title="E59">A1</font></i></a>, <a class="ref" href="cqc_the2.html#T7" target="_self" title="CQC_THE2:th.7">Th7</a></i>;<br/>
<a NAME="E6:87"/><b>then </b>
<span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p3">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 
<b>by </b><i><a class="txt" href="cqc_the2.html#E3:87"><i><font color="Green" title="E60">A2</font></i></a>, <a class="ref" href="cqc_the2.html#T22" target="_self" title="CQC_THE2:th.22">Th22</a></i>;<br/>
<b>hence </b><a NAME="E7:87"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 <b>by </b><i><a class="ref" href="cqc_the2.html#T2" target="_self" title="CQC_THE2:th.2">Th2</a></i>;<br/>

<a NAME="E8:87"/>
<font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 
<b>by </b><i><a class="ref" href="cqc_the2.html#T18" target="_self" title="CQC_THE2:th.18">Th18</a></i>;<br/>
<a NAME="E9:87"/><b>then </b><i><font color="Green" title="E61">A3</font></i>: 
<span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 
<b>by </b><i><a class="txt" href="cqc_the2.html#E13"><i><font color="Green" title="E13">Lm9</font></i></a></i>;<br/>
<a NAME="E10:87"/>
not <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="qc_lang1.html#K23" title="QC_LANG1:func.23">still_not-bound_in</a> <span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span>
 
<b>by </b><i><a class="ref" href="cqc_the2.html#T6" target="_self" title="CQC_THE2:th.6">Th6</a></i>;<br/>
<a NAME="E11:87"/><b>then </b>
not <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="qc_lang1.html#K23" title="QC_LANG1:func.23">still_not-bound_in</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span></span>)</span>
 
<b>by </b><i><a class="txt" href="cqc_the2.html#E1:87"><i><font color="Green" title="E59">A1</font></i></a>, <a class="ref" href="cqc_the2.html#T9" target="_self" title="CQC_THE2:th.9">Th9</a></i>;<br/>
<b>hence </b><a NAME="E12:87"/>
<span class="p1">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <span class="p2">(<span class="default"><a href="cqc_lang.html#K16" title="CQC_LANG:func.16">Ex</a> <font color="Maroon" title="c3">x</font>,<font color="Maroon" title="c2">q</font></span>)</span></span>)</span> is <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>
 <b>by </b><i><a class="txt" href="cqc_the2.html#E9:87"><i><font color="Green" title="E61">A3</font></i></a>, <a class="ref" href="cqc_the2.html#T22" target="_self" title="CQC_THE2:th.22">Th22</a></i>;<br/>


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