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<b>take </b>
<span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><a href="qc_lang1.html#K8">QC-WFF</a> ,<a href="substut1.html#K1" target="_self">vSUB</a> </span><a href="zfmisc_1.html#K2">:]</a></span>
;<br/>

<b>thus </b><a NAME="E1:26_1_1"/>
( <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><a href="qc_lang1.html#K8">QC-WFF</a> ,<a href="substut1.html#K1" target="_self">vSUB</a> </span><a href="zfmisc_1.html#K2">:]</a></span> is <a href="substut1.html#V1" target="_self">QC-Sub-closed</a> &amp; not <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><a href="qc_lang1.html#K8">QC-WFF</a> ,<a href="substut1.html#K1" target="_self">vSUB</a> </span><a href="zfmisc_1.html#K2">:]</a></span> is <a href="xboole_0.html#V1">empty</a> )
 <b>by </b><i><a class="ref" href="substut1.html#D16" target="_self">Def16</a>, <a class="ref" href="substut1.html#T7" target="_self">Th7</a></i>;<br/>


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