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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/>

<b>assume </b><a NAME="E1:51"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#NR1" target="_self">is_equality</a> 
 ;<br/>

<b>then consider </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font> being   <a href="zf_lang.html#NM1">Variable</a><b> such that </b><br/><a NAME="E3:51"/><i><font color="Green">E40</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>2</sub></font> <a href="zf_lang.html#K4" target="_self">'='</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="zf_lang.html#D10" target="_self">Def10</a></i>;<br/>
<a NAME="E4:51"/><i><font color="Green">E41</font></i>: 
( <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2"><a href="finseq_1.html#K12">&lt;*</a><span class="default">0</span><a href="finseq_1.html#K12">*&gt;</a></span> <a href="finseq_1.html#K8">^</a> <span class="p2"><a href="zf_lang.html#K3" target="_self">&lt;*</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="zf_lang.html#K3" target="_self">*&gt;</a></span></span>)</span> <a href="finseq_1.html#K8">^</a> <span class="p1"><a href="zf_lang.html#K3" target="_self">&lt;*</a><span class="default"><font color="Maroon">c<sub>3</sub></font></span><a href="zf_lang.html#K3" target="_self">*&gt;</a></span> &amp; <span class="p1">(<span class="default"><span class="p2"><a href="finseq_1.html#K12">&lt;*</a><span class="default">0</span><a href="finseq_1.html#K12">*&gt;</a></span> <a href="finseq_1.html#K8">^</a> <span class="p2"><a href="zf_lang.html#K3" target="_self">&lt;*</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="zf_lang.html#K3" target="_self">*&gt;</a></span></span>)</span> <a href="finseq_1.html#K8">^</a> <span class="p1"><a href="zf_lang.html#K3" target="_self">&lt;*</a><span class="default"><font color="Maroon">c<sub>3</sub></font></span><a href="zf_lang.html#K3" target="_self">*&gt;</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_1.html#K11">&lt;*</a><span class="default">0,<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font></span><a href="finseq_1.html#K11">*&gt;</a></span> )
 
<b>by </b><i><a class="txt" href="zf_lang.html#E3:51"><i><font color="Green">E40</font></i></a>, <a class="ref" href="finseq_1.html#D10">FINSEQ_1:def 10</a></i>;<br/>
<a NAME="E5:51"/>
<font color="Maroon">c<sub>1</sub></font> is <a href="zf_lang.html#V7" target="_self">atomic</a>
 
<b>by </b><i><a class="txt" href="zf_lang.html#E1:51"><i><font color="Green">E39</font></i></a>, <a class="ref" href="zf_lang.html#D15" target="_self">Def15</a></i>;<br/>
<a NAME="E6:51"/><b>then </b>
( <font color="Maroon">c<sub>1</sub></font> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>2</sub></font> &amp; <font color="Maroon">c<sub>1</sub></font> <a href="funct_1.html#K1">.</a> 3 <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>1</sub></font> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K18" target="_self">Var1</a> <font color="Maroon">c<sub>1</sub></font> &amp; <font color="Maroon">c<sub>1</sub></font> <a href="funct_1.html#K1">.</a> 3 <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K19" target="_self">Var2</a> <font color="Maroon">c<sub>1</sub></font> )
 
<b>by </b><i><a class="txt" href="zf_lang.html#E4:51"><i><font color="Green">E41</font></i></a>, <a class="ref" href="zf_lang.html#D28" target="_self">Def28</a>, <a class="ref" href="zf_lang.html#D29" target="_self">Def29</a>, <a class="ref" href="finseq_1.html#T62">FINSEQ_1:62</a></i>;<br/>
<b>hence </b><a NAME="E7:51"/>
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K18" target="_self">Var1</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="zf_lang.html#K4" target="_self">'='</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K19" target="_self">Var2</a> <font color="Maroon">c<sub>1</sub></font></span>)</span>
 <b>by </b><i><a class="txt" href="zf_lang.html#E3:51"><i><font color="Green">E40</font></i></a></i>;<br/>


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