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<b>let </b><font color="Maroon" title="c1">S1</font>, <font color="Maroon" title="c2">S2</font> be    <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of  <a href="substut1.html#K16" title="SUBSTUT1:func.16">QC-Sub-WFF</a> ;<br/>



<b>assume </b><a NAME="E1:94"/><i><font color="Green" title="E58">A1</font></i>: 
( <font color="Maroon" title="c1">S1</font> <a href="substut1.html#K19" title="SUBSTUT1:func.19">`2</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">S2</font> <a href="substut1.html#K19" title="SUBSTUT1:func.19">`2</a>  &amp;  <a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <font color="Maroon" title="c1">S1</font> is    <a href="subset_1.html#M2" title="SUBSET_1:mode.2">Element</a> of  <a href="cqc_lang.html#K4" title="CQC_LANG:func.4">CQC-WFF</a>  &amp;  <a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <font color="Maroon" title="c2">S2</font> is    <a href="subset_1.html#M2" title="SUBSET_1:mode.2">Element</a> of  <a href="cqc_lang.html#K4" title="CQC_LANG:func.4">CQC-WFF</a>  )
 ;<br/>

<a NAME="E2:94"/>
( <font color="Maroon" title="c1">S1</font> <a href="substut1.html#K19" title="SUBSTUT1:func.19">`2</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">S2</font> <a href="substut1.html#K19" title="SUBSTUT1:func.19">`2</a>  implies  <a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" title="SUBSTUT1:func.21">Sub_&amp;</a> <font color="Maroon" title="c1">S1</font>,<font color="Maroon" title="c2">S2</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <font color="Maroon" title="c1">S1</font></span>)</span> <a href="qc_lang1.html#K13" title="QC_LANG1:func.13">'&amp;'</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <font color="Maroon" title="c2">S2</font></span>)</span> )
 
<b>by </b><i><a class="ref" href="substut1.html#T31" target="_self" title="SUBSTUT1:th.31">Th31</a></i>;<br/>
<b>hence </b><a NAME="E3:94"/>
 <a href="substut1.html#K37" title="SUBSTUT1:func.37">CQC_Sub</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" title="SUBSTUT1:func.21">Sub_&amp;</a> <font color="Maroon" title="c1">S1</font>,<font color="Maroon" title="c2">S2</font></span>)</span> is    <a href="subset_1.html#M2" title="SUBSET_1:mode.2">Element</a> of  <a href="cqc_lang.html#K4" title="CQC_LANG:func.4">CQC-WFF</a> 
 <b>by </b><i><a class="txt" href="substut1.html#E1:94"><i><font color="Green" title="E58">A1</font></i></a>, <a class="ref" href="cqc_lang.html#T19" title="CQC_LANG:th.19">CQC_LANG:19</a></i>;<br/>


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