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<b>let </b><font color="Maroon">X</font> be   <a href="subset_1.html#NM2">Subset</a> of <a href="cqc_lang.html#K7">CQC-WFF</a> ;<br/><b>let </b><font color="Maroon">Y</font> be   <a href="subset_1.html#NM2">Subset</a> of <a href="cqc_lang.html#K7">CQC-WFF</a> ;<br/>



<div><i><font color="Green">E39</font></i>: <a class="txt" onclick="hs2(this)" href="javascript:()" title="9_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:9_1"/><i><font color="Green">E42</font></i>: 
<font color="Maroon">X</font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">Y</font>
 ;<br/><div><a class="txt" onclick="hs2(this)" href="javascript:()" title="9_1_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">p</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>assume </b><a NAME="E1:9_1_1"/><i><font color="Green">E43</font></i>: 
<font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font>
 ;<br/><b>then reconsider </b><font color="Maroon">p'</font> = <font color="Maroon">p</font> as    <a href="subset_1.html#M2">Element</a> of  <a href="cqc_lang.html#K7">CQC-WFF</a>  ;<br/><a NAME="E3:9_1_1"/>
<font color="Maroon">X</font> <a href="cqc_the1.html#R3">|-</a> <font color="Maroon">p'</font>
 <b>by </b><i>, , </i>;<br/><b>hence </b><a NAME="E4:9_1_1"/>
<font color="Maroon">p</font> <a href="hidden.html#R2">in</a>  <a href="cqc_the1.html#K1">Cn</a> <font color="Maroon">X</font>
 <b>by </b><i><a class="ref" href="cqc_the1.html#D9">CQC_THE1:def 9</a></i>;<br/></div><b>end;</b></div><b>hence </b><a NAME="E3:9_1"/>
<font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a>  <a href="cqc_the1.html#K1">Cn</a> <font color="Maroon">X</font>
 <b>by </b><i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a></i>;<br/></div><b>end;</b></div>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="9_2"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:9_2"/>
<font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a>  <a href="cqc_the1.html#K1">Cn</a> <font color="Maroon">X</font>
 ;<br/><a NAME="E2:9_2"/><b>then </b>
for <font color="Olive">p</font> being   <a href="subset_1.html#M2">Element</a> of  <a href="cqc_lang.html#K7">CQC-WFF</a>   st <font color="Olive">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font> holds <br/><font color="Maroon">X</font> <a href="cqc_the1.html#R3">|-</a> <font color="Olive">p</font>
 <b>by </b><i><a class="ref" href="cqc_the1.html#D9">CQC_THE1:def 9</a></i>;<br/><b>hence </b><a NAME="E3:9_2"/>
<font color="Maroon">X</font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">Y</font>
 <b>by </b><i/>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E3:9"/>
( <font color="Maroon">X</font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">Y</font> iff <font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a>  <a href="cqc_the1.html#K1">Cn</a> <font color="Maroon">X</font> )
 <b>by </b><i/>;<br/>


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