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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>set </b><font color="Maroon" title="c3">P</font> = <font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c2">q</font>;<br/>
<b>set </b><font color="Maroon" title="c4">Q</font> = <font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</font>;<br/>
<a NAME="E1:33"/><i><font color="Green" title="E24">A1</font></i>: 
<span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</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="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</font></span>)</span> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a> 
 
<b>by </b><i><a class="ref" href="procal_1.html#T8" target="_self" title="PROCAL_1:th.8">Th8</a></i>;<br/>
<a NAME="E2:33"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</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#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a> 
 
<b>by </b><i><a class="ref" href="procal_1.html#T8" target="_self" title="PROCAL_1:th.8">Th8</a></i>;<br/>
<a NAME="E3:33"/><b>then </b>
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</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="p2">(<span class="default"><font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</font></span>)</span></span>)</span> <a href="cqc_lang.html#K11" title="CQC_LANG:func.11">'&amp;'</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</font></span>)</span> <a href="cqc_lang.html#K12" title="CQC_LANG:func.12">=&gt;</a> <span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a> 
 
<b>by </b><i><a class="txt" href="procal_1.html#E1:33"><i><font color="Green" title="E24">A1</font></i></a>, <a class="txt" href="procal_1.html#E33"><i><font color="Green" title="E23">Lm4</font></i></a></i>;<br/>
<b>hence </b><a NAME="E4:33"/>
<span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="cqc_lang.html#K14" title="CQC_LANG:func.14">&lt;=&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">q</font> <a href="cqc_lang.html#K13" title="CQC_LANG:func.13">'or'</a> <font color="Maroon" title="c1">p</font></span>)</span> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a> 
 <b>by </b><i><a class="ref" href="qc_lang2.html#D4" title="QC_LANG2:def.4">QC_LANG2:def 4</a></i>;<br/>


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