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<b>let </b><font color="Maroon">D2</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">D1</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">F1</font> be    <a href="seqfunc.html#M1" target="_self">Functional_Sequence</a> of <font color="Maroon">D1</font>,<font color="Maroon">D2</font>;<br/><b>let </b><font color="Maroon">F2</font> be    <a href="seqfunc.html#M1" target="_self">Functional_Sequence</a> of <font color="Maroon">D1</font>,<font color="Maroon">D2</font>;<br/>







<b>assume </b><a NAME="E1:6"/>
for <font color="Olive">n</font> being   <a href="subset_1.html#M2">Element</a> of  <a href="numbers.html#K5">NAT</a>  holds  <font color="Maroon">F1</font> <a href="seqfunc.html#K1" target="_self">.</a> <font color="Olive">n</font> <a href="hidden.html#R1">=</a> <font color="Maroon">F2</font> <a href="seqfunc.html#K1" target="_self">.</a> <font color="Olive">n</font>
 ;<br/>

<a NAME="E2:6"/><b>then </b>
for <font color="Olive">x</font> being   <a href="hidden.html#M1">set</a>   st <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K5">NAT</a>  holds <br/><font color="Maroon">F1</font> <a href="funct_1.html#K1">.</a> <font color="Olive">x</font> <a href="hidden.html#R1">=</a> <font color="Maroon">F2</font> <a href="funct_1.html#K1">.</a> <font color="Olive">x</font>
 
;<br/>
<b>hence </b><a NAME="E3:6"/>
<font color="Maroon">F1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">F2</font>
 <b>by </b><i/>;<br/>


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