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<b>let </b><font color="Maroon">c<sub>1</sub></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="E1:66"/><i><font color="Green">E49</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="cqc_the1.html#NR1" target="_self">is_a_theory</a> 
 ;<br/>

<a NAME="E2:66"/>
 <a href="subset_1.html#K1">{}</a> <a href="cqc_lang.html#K7">CQC-WFF</a>  <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="ref" href="xboole_1.html#T2">XBOOLE_1:2</a></i>;<br/>
<a NAME="E3:66"/><b>then </b>
 <a href="cqc_the1.html#K1" target="_self">Cn</a> <span class="p1">(<span class="default"><a href="subset_1.html#K1">{}</a> <a href="cqc_lang.html#K7">CQC-WFF</a> </span>)</span> <a href="tarski.html#R1">c=</a>  <a href="cqc_the1.html#K1" target="_self">Cn</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="ref" href="cqc_the1.html#T39" target="_self">Th39</a></i>;<br/>
<b>hence </b><a NAME="E4:66"/>
 <a href="cqc_the1.html#K4" target="_self">TAUT</a>  <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="cqc_the1.html#E1:66"><i><font color="Green">E49</font></i></a>, <a class="ref" href="cqc_the1.html#T41" target="_self">Th41</a></i>;<br/>


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