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<b>let </b><font color="Maroon">F</font> be   <a href="funct_2.html#NM1">Function</a> of <font color="Maroon">X</font>,<font color="Maroon">D</font>, <font color="Maroon">G</font> be   <a href="funct_2.html#NM1">Function</a> of <font color="Maroon">X</font>,<font color="Maroon">D</font>;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:23_1_2"/><i><font color="Green">E32</font></i>: 
for <font color="Olive">p</font> being   <a href="subset_1.html#M1">Element</a> of <font color="Maroon">X</font> holds  <font color="Olive">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">F</font> <a href="funct_2.html#K3">.</a> <font color="Olive">p</font>
 <b>and </b><br/><a NAME="E2:23_1_2"/><i><font color="Green">E33</font></i>: 
for <font color="Olive">p</font> being   <a href="subset_1.html#M1">Element</a> of <font color="Maroon">X</font> holds  <font color="Olive">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">G</font> <a href="funct_2.html#K3">.</a> <font color="Olive">p</font>
 ;<br/>

<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="23_1_2_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">x</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">X</font>;<br/><a NAME="E1:23_1_2_1"/><i><font color="Green">E34</font></i>: 
( <font color="Maroon">F</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> is   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">X</font> &amp; <font color="Maroon">G</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> is   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">X</font> )
 <b>by </b><i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a></i>;<br/><a NAME="E2:23_1_2_1"/>
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">F</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> &amp; <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">G</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> )
 <b>by </b><i>, </i>;<br/><a NAME="E3:23_1_2_1"/><b>then </b>
not <font color="Maroon">F</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">G</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font>
 <b>by </b><i><a class="ref" href="xboole_0.html#T3">XBOOLE_0:3</a></i>;<br/><b>hence </b><a NAME="E4:23_1_2_1"/>
<font color="Maroon">F</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font> <a href="hidden.html#R1">=</a> <font color="Maroon">G</font> <a href="funct_2.html#K3">.</a> <font color="Maroon">x</font>
 <b>by </b><i><a class="ref" href="borsuk_1.html#T4" target="_self">Th4</a>, <a class="ref" href="eqrel_1.html#D6">EQREL_1:def 6</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E4:23_1_2"/>
<font color="Maroon">F</font> <a href="funct_2.html#R2">=</a> <font color="Maroon">G</font>
 <b>by </b><i><a class="ref" href="funct_2.html#T113">FUNCT_2:113</a></i>;<br/>


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