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<b>let </b><font color="Maroon">n</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">M</font> be    <a href="finseq_1.html#M2">FinSequence</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">m</font> be    <a href="finseq_1.html#M2">FinSequence</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">k</font> be    <a href="finseq_1.html#M2">FinSequence</a> of  <a href="numbers.html#K5">NAT</a> ;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:73"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">M</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="idea_1.html#K15" target="_self">IDEA_P</a> <font color="Maroon">k</font>,<font color="Maroon">n</font></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">m</font>
 <b>and </b><br/><a NAME="E2:73"/><i><font color="Green">E35</font></i>: 
 <a href="finseq_1.html#K3">len</a> <font color="Maroon">m</font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 4
 ;<br/>

<a NAME="E3:73"/><i><font color="Green">E36</font></i>: 
<font color="Maroon">M</font> <a href="hidden.html#R1">=</a>  <a href="idea_1.html#K11" target="_self">IDEAoperationA</a> <span class="p1">(<span class="default"><a href="idea_1.html#K13" target="_self">IDEAoperationC</a> <span class="p2">(<span class="default"><a href="idea_1.html#K12" target="_self">IDEAoperationB</a> <font color="Maroon">m</font>,<font color="Maroon">k</font>,<font color="Maroon">n</font></span>)</span></span>)</span>,<font color="Maroon">k</font>,<font color="Maroon">n</font>
 
<b>by </b><i>, </i>;<br/>
 <a href="finseq_1.html#K3">len</a> <font color="Maroon">m</font> = 
 <a href="finseq_1.html#K3">len</a> <span class="p1">(<span class="default"><a href="idea_1.html#K12" target="_self">IDEAoperationB</a> <font color="Maroon">m</font>,<font color="Maroon">k</font>,<font color="Maroon">n</font></span>)</span>
<b>by </b><i/>
<br/>.= 
 <a href="finseq_1.html#K3">len</a> <span class="p1">(<span class="default"><a href="idea_1.html#K13" target="_self">IDEAoperationC</a> <span class="p2">(<span class="default"><a href="idea_1.html#K12" target="_self">IDEAoperationB</a> <font color="Maroon">m</font>,<font color="Maroon">k</font>,<font color="Maroon">n</font></span>)</span></span>)</span>
<b>by </b><i/>
;<br/>
<b>hence </b><a NAME="E5:73"/>
(  <a href="finseq_1.html#K3">len</a> <font color="Maroon">M</font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 4 &amp; <font color="Maroon">M</font> <a href="wsierp_1.html#K3">.</a> 1 <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">n</font> &amp; <font color="Maroon">M</font> <a href="wsierp_1.html#K3">.</a> 2 <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">n</font> &amp; <font color="Maroon">M</font> <a href="wsierp_1.html#K3">.</a> 3 <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">n</font> &amp; <font color="Maroon">M</font> <a href="wsierp_1.html#K3">.</a> 4 <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">n</font> )
 <b>by </b><i>, , , </i>;<br/>


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