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<b>let </b><font color="Maroon">x</font> be   <a href="zf_lang.html#NM1">Variable</a>;<br/><b>let </b><font color="Maroon">y</font> be   <a href="zf_lang.html#NM1">Variable</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="E1:67"/>
<font color="Maroon">H</font> <a href="zf_lang.html#R1" target="_self">is_immediate_constituent_of</a> <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font>
 ;<br/>

<a NAME="E2:67"/><b>then </b><i><font color="Green">E31</font></i>: 
( <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">H</font> or  ex <font color="Olive">H1</font> being  <a href="zf_lang.html#NM2">ZF-formula</a> st <br/>( <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H</font> <a href="zf_lang.html#K7" target="_self">'&amp;'</a> <font color="Olive">H1</font> or <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <font color="Olive">H1</font> <a href="zf_lang.html#K7" target="_self">'&amp;'</a> <font color="Maroon">H</font> ) or  ex <font color="Olive">z</font> being  <a href="zf_lang.html#NM1">Variable</a> st <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K8" target="_self">All</a> <font color="Olive">z</font>,<font color="Maroon">H</font> )
 
<b>by </b><i><a class="ref" href="zf_lang.html#D9" target="_self">Def9</a></i>;<br/>
<a NAME="E3:67"/><i><font color="Green">E32</font></i>: 
( <span class="p1">(<span class="default"><font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font></span>)</span> <a href="funct_1.html#K1">.</a> 1 <a href="hidden.html#R1">=</a> 0 &amp; <span class="p1">(<span class="default"><a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">H</font></span>)</span> <a href="funct_1.html#K1">.</a> 1 <a href="hidden.html#R1">=</a> 2 )
 
<b>by </b><i>, </i>;<br/>
<b>then consider </b><font color="Maroon">z</font> being   <a href="zf_lang.html#NM1">Variable</a><b> such that </b><br/><a NAME="E5:67"/><i><font color="Green">E35</font></i>: 
<font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K8" target="_self">All</a> <font color="Maroon">z</font>,<font color="Maroon">H</font>
 <b>by </b><i>, </i>;<br/>
<b>thus </b><a NAME="E6:67"/>
contradiction
 <b>by </b><i>, , </i>;<br/>


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