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<b>let </b><font color="Maroon">F</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="qc_lang1.html#K8">QC-WFF</a> ;<br/><b>let </b><font color="Maroon">k</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">P</font> be   <a href="qc_lang1.html#NM6">QC-pred_symbol</a> of <font color="Maroon">k</font>;<br/><b>let </b><font color="Maroon">V</font> be    <a href="qc_lang1.html#M1">QC-variable_list</a> of <font color="Maroon">k</font>;<br/>







<b>assume </b><a NAME="E1:63"/>
<font color="Maroon">F</font> <a href="qc_lang2.html#R3" target="_self">is_proper_subformula_of</a> <font color="Maroon">P</font> <a href="qc_lang1.html#K9">!</a> <font color="Maroon">V</font>
 ;<br/>

<a NAME="E2:63"/><b>then </b>
 ex <font color="Olive">G</font> being   <a href="subset_1.html#M1">Element</a> of  <a href="qc_lang1.html#K8">QC-WFF</a>  st <font color="Olive">G</font> <a href="qc_lang2.html#R1" target="_self">is_immediate_constituent_of</a> <font color="Maroon">P</font> <a href="qc_lang1.html#K9">!</a> <font color="Maroon">V</font>
 
<b>by </b><i><a class="ref" href="qc_lang2.html#T8" target="_self">Th8</a></i>;<br/>
<b>hence </b><a NAME="E3:63"/>
contradiction
 <b>by </b><i/>;<br/>


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