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<b>consider </b><font color="Maroon">x</font> being    <a href="petri.html#M1" target="_self">Element</a> of <font color="Maroon">r</font>;<br/>
<b>consider </b><font color="Maroon">y</font> being    <a href="hidden.html#M1">set</a> , <font color="Maroon">z</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E3:26_1_1"/><i><font color="Green">E18</font></i>: 
<font color="Maroon">x</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">y</font>,<font color="Maroon">z</font></span><a href="tarski.html#K4">]</a></span>
 <b>by </b><i><a class="ref" href="relat_1.html#D1">RELAT_1:def 1</a></i>;<br/>
<a NAME="E4:26_1_1"/>
<span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">z</font>,<font color="Maroon">y</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">r</font> <a href="relset_1.html#K6">~</a> 
 
<b>by </b><i>, <a class="ref" href="relat_1.html#D7">RELAT_1:def 7</a></i>;<br/>
<b>hence </b><a NAME="E5:26_1_1"/>
<font color="Maroon">r</font> <a href="relat_1.html#K4">~</a>  is  non <a href="xboole_0.html#V1">empty</a>  <a href="relset_1.html#M2">Relation</a> of <font color="Maroon">B</font>,<font color="Maroon">A</font>
 ;<br/>


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