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

<b>assume </b><a NAME="E1:38"/>
<font color="Maroon">H</font> <a href="zf_lang.html#NR1" target="_self">is_equality</a> 
 ;<br/>

<b>then consider </b><font color="Maroon">x</font> being   <a href="zf_lang.html#NM1">Variable</a>, <font color="Maroon">y</font> being   <a href="zf_lang.html#NM1">Variable</a><b> such that </b><br/><a NAME="E3:38"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">H</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x</font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">y</font>
 <b>by </b><i/>;<br/>
<a NAME="E4:38"/>
<font color="Maroon">H</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_1.html#K11">&lt;*</a><span class="default">0,<font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="finseq_1.html#K11">*&gt;</a></span>
 
<b>by </b><i>, <a class="ref" href="finseq_1.html#D10">FINSEQ_1:def 10</a></i>;<br/>
<b>hence </b><a NAME="E5:38"/>
<font color="Maroon">H</font> <a href="funct_1.html#K1">.</a> 1 <a href="hidden.html#R1">=</a> 0
 <b>by </b><i><a class="ref" href="finseq_1.html#T62">FINSEQ_1:62</a></i>;<br/>


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