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<b>let </b><font color="Maroon">X1</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> , <font color="Maroon">Y1</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> , <font color="Maroon">X2</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> , <font color="Maroon">Y2</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">f</font> be   <a href="funct_2.html#NM1">Function</a> of <font color="Maroon">X1</font>,<font color="Maroon">X2</font>;<br/><b>let </b><font color="Maroon">g</font> be   <a href="funct_2.html#NM1">Function</a> of <font color="Maroon">Y1</font>,<font color="Maroon">Y2</font>;<br/>





<a NAME="E1:5"/><i><font color="Green">E25</font></i>: 
(  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <font color="Maroon">X1</font> &amp;  <a href="relset_1.html#K4">dom</a> <font color="Maroon">g</font> <a href="hidden.html#R1">=</a> <font color="Maroon">Y1</font> &amp;  <a href="relset_1.html#K4">dom</a> <span class="p1">(<span class="default"><font color="Maroon">f</font> <a href="lang1.html#K16">*</a> </span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">X1</font> <a href="finseq_2.html#K3">*</a>  &amp;  <a href="relset_1.html#K4">dom</a> <span class="p1">(<span class="default"><font color="Maroon">g</font> <a href="lang1.html#K16">*</a> </span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">Y1</font> <a href="finseq_2.html#K3">*</a>  )
 
<b>by </b><i><a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<b>assume </b><a NAME="E2:5"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">f</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">g</font>
 ;<br/>

<a NAME="E3:5"/><b>then </b>
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">g</font>
 
<b>by </b><i><a class="ref" href="relat_1.html#T25">RELAT_1:25</a></i>;<br/>
<a NAME="E4:5"/><b>then </b><i><font color="Green">E27</font></i>: 
<font color="Maroon">X1</font> <a href="finseq_2.html#K3">*</a>  <a href="tarski.html#R1">c=</a> <font color="Maroon">Y1</font> <a href="finseq_2.html#K3">*</a> 
 
<b>by </b><i>, <a class="ref" href="finseq_1.html#T83">FINSEQ_1:83</a></i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="5_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>assume </b><a NAME="E1:5_1"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X1</font> <a href="finseq_2.html#K3">*</a> 
 ;<br/><b>then reconsider </b><font color="Maroon">p</font> = <font color="Maroon">x</font> as    <a href="finseq_2.html#M2">Element</a> of <font color="Maroon">X1</font> <a href="finseq_2.html#K3">*</a>  ;<br/><a NAME="E3:5_1"/>
( <span class="p1">(<span class="default"><a href="relset_1.html#K5">rng</a> <font color="Maroon">p</font></span>)</span> <a href="subset_1.html#K8">/\</a> <font color="Maroon">Y1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">X1</font> &amp; <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X1</font> <a href="finseq_2.html#K3">*</a>  )
 ;<br/><a NAME="E4:5_1"/><b>then </b>
( <span class="p1">(<span class="default"><font color="Maroon">f</font> <a href="lang1.html#K16">*</a> </span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <font color="Maroon">f</font> <a href="lang1.html#K15">*</a> <font color="Maroon">p</font> &amp; <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y1</font> <a href="finseq_2.html#K3">*</a>  &amp; <font color="Maroon">f</font> <a href="lang1.html#K15">*</a> <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <font color="Maroon">g</font> <a href="partfun1.html#K1">*</a> <font color="Maroon">p</font> )
 <b>by </b><i>, , , , <a class="ref" href="lang1.html#D14">LANG1:def 14</a></i>;<br/><b>hence </b><a NAME="E5:5_1"/>
<span class="p1">(<span class="default"><font color="Maroon">f</font> <a href="lang1.html#K16">*</a> </span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">x</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">g</font> <a href="lang1.html#K16">*</a> </span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">x</font>
 <b>by </b><i><a class="ref" href="lang1.html#D14">LANG1:def 14</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E6:5"/>
<font color="Maroon">f</font> <a href="lang1.html#K16">*</a>  <a href="tarski.html#R1">c=</a> <font color="Maroon">g</font> <a href="lang1.html#K16">*</a> 
 <b>by </b><i>, , <a class="ref" href="grfunc_1.html#T8">GRFUNC_1:8</a></i>;<br/>


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