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<b>let </b><font color="Maroon">x1</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">x2</font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="funct_1.html#D8">FUNCT_1:def 8</a><br/>

<b>set </b><font color="Maroon">f</font> =  <a href="funct_3.html#K12">delta</a> <font color="Maroon">X</font>;<br/>
<b>assume </b><b>that </b><br/><a NAME="E1:6_1_1"/><i><font color="Green">E36</font></i>: 
<font color="Maroon">x1</font> <a href="hidden.html#R2">in</a>  <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>
 <b>and </b><br/><a NAME="E2:6_1_1"/><i><font color="Green">E38</font></i>: 
<font color="Maroon">x2</font> <a href="hidden.html#R2">in</a>  <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>
 <b>and </b><br/><a NAME="E3:6_1_1"/><i><font color="Green">E39</font></i>: 
<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">x1</font> <a href="hidden.html#R1">=</a> <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">x2</font>
 ;<br/>

<a NAME="E4:6_1_1"/><i><font color="Green">E46</font></i>: 
<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">x1</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x1</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="E5:6_1_1"/>
<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">x2</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">x2</font>,<font color="Maroon">x2</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/>
<b>hence </b><a NAME="E6:6_1_1"/>
<font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x2</font>
 <b>by </b><i>, , <a class="ref" href="zfmisc_1.html#T33">ZFMISC_1:33</a></i>;<br/>


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