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

<b>let </b><font color="Maroon">G</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">H</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/>



<b>assume </b><a NAME="E1:98"/>
<font color="Maroon">G</font> <a href="hidden.html#R2">in</a>  <a href="zf_lang.html#K29" target="_self">Subformulae</a> <font color="Maroon">H</font>
 ;<br/>

<a NAME="E2:98"/><b>then </b>
 ex <font color="Olive">F</font> being  <a href="zf_lang.html#NM2">ZF-formula</a> st <br/>( <font color="Olive">F</font> <a href="hidden.html#R1">=</a> <font color="Maroon">G</font> &amp; <font color="Olive">F</font> <a href="zf_lang.html#R2" target="_self">is_subformula_of</a> <font color="Maroon">H</font> )
 
<b>by </b><i><a class="ref" href="zf_lang.html#T34" target="_self">Th34</a></i>;<br/>
<b>hence </b><a NAME="E3:98"/>
<font color="Maroon">G</font> <a href="zf_lang.html#R2" target="_self">is_subformula_of</a> <font color="Maroon">H</font>
 ;<br/>


</div>
