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<b>let </b><font color="Maroon" title="c1">H</font> be   <a href="zf_lang.html#NM2" title="ZF_LANG:NM.2">ZF-formula</a>;<br/>

<b>assume </b><a NAME="E1:39"/>
<font color="Maroon" title="c1">H</font> <a href="zf_lang.html#NR2" title="ZF_LANG:NR.2">is_membership</a> 
 ;<br/>

<b>then consider </b><font color="Maroon" title="c2">x</font>, <font color="Maroon" title="c3">y</font> being   <a href="zf_lang.html#NM1" title="ZF_LANG:NM.1">Variable</a><b> such that </b><br/><a NAME="E3:39"/><i><font color="Green" title="E26">A1</font></i>: 
<font color="Maroon" title="c1">H</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">x</font> <a href="zf_lang.html#K5" title="ZF_LANG:func.5">'in'</a> <font color="Maroon" title="c3">y</font>
 <b>by </b><i><a class="ref" href="zf_lang.html#D11" target="_self" title="ZF_LANG:def.11">Def11</a></i>;<br/>
<a NAME="E4:39"/>
<font color="Maroon" title="c1">H</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1"><a href="finseq_1.html#K11" title="FINSEQ_1:func.11">&lt;*</a><span class="default">1,<font color="Maroon" title="c2">x</font>,<font color="Maroon" title="c3">y</font></span><a href="finseq_1.html#K11" title="FINSEQ_1:func.11">*&gt;</a></span>
 
<b>by </b><i><a class="txt" href="zf_lang.html#E3:39"><i><font color="Green" title="E26">A1</font></i></a>, <a class="ref" href="finseq_1.html#D10" title="FINSEQ_1:def.10">FINSEQ_1:def 10</a></i>;<br/>
<b>hence </b><a NAME="E5:39"/>
<font color="Maroon" title="c1">H</font> <a href="funct_1.html#K1" title="FUNCT_1:func.1">.</a> 1 <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> 1
 <b>by </b><i><a class="ref" href="finseq_1.html#T62" title="FINSEQ_1:th.62">FINSEQ_1:62</a></i>;<br/>


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