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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="zf_lang.html#NM1">Variable</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/>



<a NAME="E1:74"/>
for <font color="Olive">b<sub>1</sub></font> being  <a href="funct_2.html#NM1">Function</a> of  <a href="zf_lang.html#K1">VAR</a> ,<font color="Maroon">c<sub>2</sub></font> holds <font color="Maroon">c<sub>2</sub></font>,<font color="Olive">b<sub>1</sub></font> <a href="zf_model.html#R1">|=</a> <font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K4">'='</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="ref" href="zf_lang1.html#T89" target="_self">Th89</a></i>;<br/>
<b>hence </b><a NAME="E2:74"/>
<font color="Maroon">c<sub>2</sub></font> <a href="zf_model.html#R2">|=</a> <font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K4">'='</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="ref" href="zf_model.html#D5">ZF_MODEL:def 5</a></i>;<br/>


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