<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">S1</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="substut1.html#K16" target="_self">QC-Sub-WFF</a> ;<br/><b>let </b><font color="Maroon">S2</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="substut1.html#K16" target="_self">QC-Sub-WFF</a> ;<br/>



<b>assume </b><a NAME="E1:94"/><i><font color="Green">E40</font></i>: 
( <font color="Maroon">S1</font> <a href="substut1.html#K19" target="_self">`2</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">S2</font> <a href="substut1.html#K19" target="_self">`2</a>  &amp;  <a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">S1</font> is    <a href="subset_1.html#M2">Element</a> of  <a href="cqc_lang.html#K7">CQC-WFF</a>  &amp;  <a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">S2</font> is    <a href="subset_1.html#M2">Element</a> of  <a href="cqc_lang.html#K7">CQC-WFF</a>  )
 ;<br/>

<a NAME="E2:94"/>
( <font color="Maroon">S1</font> <a href="substut1.html#K19" target="_self">`2</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">S2</font> <a href="substut1.html#K19" target="_self">`2</a>  implies  <a href="substut1.html#K37" target="_self">CQC_Sub</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">S1</font>,<font color="Maroon">S2</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">S1</font></span>)</span> <a href="qc_lang1.html#K13">'&amp;'</a> <span class="p1">(<span class="default"><a href="substut1.html#K37" target="_self">CQC_Sub</a> <font color="Maroon">S2</font></span>)</span> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E3:94"/>
 <a href="substut1.html#K37" target="_self">CQC_Sub</a> <span class="p1">(<span class="default"><a href="substut1.html#K21" target="_self">Sub_&amp;</a> <font color="Maroon">S1</font>,<font color="Maroon">S2</font></span>)</span> is    <a href="subset_1.html#M2">Element</a> of  <a href="cqc_lang.html#K7">CQC-WFF</a> 
 <b>by </b><i>, <a class="ref" href="cqc_lang.html#T19">CQC_LANG:19</a></i>;<br/>


</div>
