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<b>defpred </b><font color="Maroon">S<sub>1</sub></font>[   <a href="hidden.html#M1">set</a> ] <b>means </b> ex <font color="Olive">x</font> being  <a href="qc_lang1.html#NM3">bound_QC-variable</a> st <br/>( <font color="Olive">x</font> <a href="hidden.html#R1">=</a> <font color="Maroon">a<sub>1</sub></font> &amp; not <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="qc_lang1.html#K23">still_not-bound_in</a> <font color="Maroon">p</font> );<br/>
<b>consider </b><font color="Maroon">X</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E2:99_1_1"/><i><font color="Green">E55</font></i>: 
for <font color="Olive">b</font> being   <a href="hidden.html#M1">set</a>  holds <br/> ( <font color="Olive">b</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> iff ( <font color="Olive">b</font> <a href="hidden.html#R2">in</a>  <a href="qc_lang1.html#K2">bound_QC-variables</a>  &amp; <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">b</font>] ) )
 <b>from </b><i><a class="ref" href="xboole_0.html#S1">XBOOLE_0:sch 1</a>();<br/></i>
<b>take </b>
<font color="Maroon">X</font>
;<br/>

<b>thus </b><a NAME="E3:99_1_1"/>
for <font color="Olive">b</font> being   <a href="hidden.html#M1">set</a>  holds <br/> ( <font color="Olive">b</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> iff  ex <font color="Olive">x</font> being  <a href="qc_lang1.html#NM3">bound_QC-variable</a> st <br/>( <font color="Olive">x</font> <a href="hidden.html#R1">=</a> <font color="Olive">b</font> &amp; not <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="qc_lang1.html#K23">still_not-bound_in</a> <font color="Maroon">p</font> ) )
 <b>by </b><i/>;<br/>


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