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<span class="kw">let </span><font color="Maroon" title="c1">s</font> be   <a href="qc_lang1.html#NM8" title="QC_LANG1:NM.8">QC-formula</a>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> ( <font color="Maroon" title="c1">s</font> is  <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>  iff <font color="Maroon" title="c1">s</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a>  )</span><br/>

<a NAME="E1:66"/>
( <font color="Maroon" title="c1">s</font> is  <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>  iff  <a href="subset_1.html#K1" title="SUBSET_1:func.1">{}</a> <a href="cqc_lang.html#K3" title="CQC_LANG:func.3">CQC-WFF</a> <a href="cqc_the1.html#R3" title="CQC_THE1:pred.3">|-</a> <font color="Maroon" title="c1">s</font> )
 
<span class="kw">by</span> <span class="lab"><a class="ref" href="cqc_the1.html#D9" target="_self" title="CQC_THE1:def.9">Def10</a></span>;<br/>
<span class="kw">hence </span><a NAME="E2:66"/>
( <font color="Maroon" title="c1">s</font> is  <a href="cqc_the1.html#V2" title="CQC_THE1:attr.2">valid</a>  iff <font color="Maroon" title="c1">s</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="cqc_the1.html#K4" title="CQC_THE1:func.4">TAUT</a>  )
 <span class="kw">by</span> <span class="lab"><a class="ref" href="cqc_the1.html#D8" target="_self" title="CQC_THE1:def.8">Def9</a></span>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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