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<div><span class="kw">theorem </span><a NAME="T21"><span class="comment"><font color="firebrick">:: QC_LANG2:21</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">A</font> being    <a href="qc_lang1.html#M1" title="QC_LANG1:mode.1">QC-alphabet</a> <br/>  for <font color="Olive" title="b2">p1</font>, <font color="Olive" title="b3">p2</font> being    <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of  <a href="qc_lang1.html#K9" title="QC_LANG1:func.9">QC-WFF</a> <font color="Olive" title="b1">A</font><br/>  for <font color="Olive" title="b4">x1</font>, <font color="Olive" title="b5">x2</font>, <font color="Olive" title="b6">y1</font>, <font color="Olive" title="b7">y2</font>, <font color="Olive" title="b8">z1</font>, <font color="Olive" title="b9">z2</font> being   <a href="qc_lang1.html#NM5" title="QC_LANG1:NM.5">bound_QC-variable</a> of <font color="Olive" title="b1">A</font>  st  <a href="qc_lang2.html#K8" title="QC_LANG2:func.8">All</a> (<font color="Olive" title="b4">x1</font>,<font color="Olive" title="b6">y1</font>,<font color="Olive" title="b8">z1</font>,<font color="Olive" title="b2">p1</font>) <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="qc_lang2.html#K8" title="QC_LANG2:func.8">All</a> (<font color="Olive" title="b5">x2</font>,<font color="Olive" title="b7">y2</font>,<font color="Olive" title="b9">z2</font>,<font color="Olive" title="b3">p2</font>) holds <br/>( <font color="Olive" title="b4">x1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Olive" title="b5">x2</font> &amp; <font color="Olive" title="b6">y1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Olive" title="b7">y2</font> &amp; <font color="Olive" title="b8">z1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Olive" title="b9">z2</font> &amp; <font color="Olive" title="b2">p1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Olive" title="b3">p2</font> )</div></div>
