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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/>



<b>assume </b><a NAME="E1:14"/>
<font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font>
 ;<br/>

<a NAME="E2:14"/><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">X</font> holds <br/><font color="Maroon">Y</font> <a href="cqc_the1.html#R3">|-</a> <font color="Olive">p</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E3:14"/>
<font color="Maroon">Y</font> <a href="cqc_the3.html#R2" target="_self">|-</a> <font color="Maroon">X</font>
 <b>by </b><i/>;<br/>


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