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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">Y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">f</font> be   <a href="partfun1.html#NM1">PartFunc</a> of <font color="Maroon">X</font>,<font color="Maroon">Y</font>, <font color="Maroon">g</font> be   <a href="partfun1.html#NM1">PartFunc</a> of <font color="Maroon">X</font>,<font color="Maroon">Y</font>;<br/>





<b>assume </b><a NAME="E1:121"/><i><font color="Green">E20</font></i>: 
for <font color="Olive">y</font> being   <a href="hidden.html#M1">set</a>   holds <font color="Maroon">Y</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <span class="p1"><a href="tarski.html#K1">{</a><span class="default"><font color="Olive">y</font></span><a href="tarski.html#K1">}</a></span>
 ;<br/>

<b>assume </b><a NAME="E2:121"/>
 <a href="partfun1.html#K5">TotFuncs</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a>  <a href="partfun1.html#K5">TotFuncs</a> <font color="Maroon">g</font>
 ;<br/>

<a NAME="E3:121"/><b>then </b>
( <font color="Maroon">g</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">f</font> &amp; <font color="Maroon">f</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">g</font> )
 
<b>by </b><i>, </i>;<br/>
<b>hence </b><a NAME="E4:121"/>
<font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <font color="Maroon">g</font>
 <b>by </b><i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>


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