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<b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">A</font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">X</font>;<br/>



<b>set </b><font color="Maroon">f</font> =  <a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font>;<br/>
<a NAME="E1:5"/><i><font color="Green">E34</font></i>: 
 <a href="relset_1.html#K4">dom</a> <span class="p1">(<span class="default"><a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">X</font>
 
<b>by </b><i><a class="ref" href="funct_3.html#D7">FUNCT_3:def 7</a></i>;<br/>
<b>thus </b><a NAME="E2:5"/>
<span class="p1">(<span class="default"><a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font></span>)</span> <a href="relset_1.html#K11">"</a> <span class="p1"><a href="mcart_1.html#K12">[:</a><span class="default"><font color="Maroon">A</font>,<font color="Maroon">A</font></span><a href="mcart_1.html#K12">:]</a></span> <a href="tarski.html#R1">c=</a> <font color="Maroon">A</font>
 <b>by </b><i/>; <i><font color="Red">:: according to </font></i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a><br/>

<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a><br/>

<b>assume </b><a NAME="E3:5"/><i><font color="Green">E35</font></i>: 
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font>
 ;<br/>

<a NAME="E4:5"/><b>then </b>
<span class="p1">(<span class="default"><a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font></span>)</span> <a href="funct_1.html#K1">.</a> <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">x</font>,<font color="Maroon">x</font></span><a href="tarski.html#K4">]</a></span>
 
<b>by </b><i><a class="ref" href="funct_3.html#D7">FUNCT_3:def 7</a></i>;<br/>
<a NAME="E5:5"/><b>then </b>
<span class="p1">(<span class="default"><a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="mcart_1.html#K12">[:</a><span class="default"><font color="Maroon">A</font>,<font color="Maroon">A</font></span><a href="mcart_1.html#K12">:]</a></span>
 
<b>by </b><i>, <a class="ref" href="zfmisc_1.html#T106">ZFMISC_1:106</a></i>;<br/>
<b>hence </b><a NAME="E6:5"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <span class="p1">(<span class="default"><a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font></span>)</span> <a href="relset_1.html#K11">"</a> <span class="p1"><a href="mcart_1.html#K12">[:</a><span class="default"><font color="Maroon">A</font>,<font color="Maroon">A</font></span><a href="mcart_1.html#K12">:]</a></span>
 <b>by </b><i>, , <a class="ref" href="funct_1.html#D13">FUNCT_1:def 13</a></i>;<br/>


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