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<b>let </b><font color="Maroon">K</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">POS</font>, <font color="Maroon">M</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">POS</font>;<br/>

<b>assume </b><a NAME="E1:81_1_1"/>
<font color="Maroon">K</font> <a href="analmetr.html#R8" target="_self">//</a> <font color="Maroon">M</font>
 ;<br/>

<b>then consider </b><font color="Maroon">a</font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">POS</font>, <font color="Maroon">b</font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">POS</font>, <font color="Maroon">c</font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">POS</font>, <font color="Maroon">d</font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">POS</font><b> such that </b><br/><a NAME="E3:81_1_1"/><i><font color="Green">E38</font></i>: 
( <font color="Maroon">a</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">b</font> &amp; <font color="Maroon">c</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">d</font> &amp; <font color="Maroon">K</font> <a href="hidden.html#R1">=</a>  <a href="analmetr.html#K4" target="_self">Line</a> <font color="Maroon">a</font>,<font color="Maroon">b</font> &amp; <font color="Maroon">M</font> <a href="hidden.html#R1">=</a>  <a href="analmetr.html#K4" target="_self">Line</a> <font color="Maroon">c</font>,<font color="Maroon">d</font> )
 <b>and </b><br/><a NAME="E4:81_1_1"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c</font>,<font color="Maroon">d</font>
 <b>by </b><i><a class="ref" href="analmetr.html#T11" target="_self">Th11</a></i>;<br/>
<b>reconsider </b><font color="Maroon">a'</font> = <font color="Maroon">a</font>, <font color="Maroon">b'</font> = <font color="Maroon">b</font>, <font color="Maroon">c'</font> = <font color="Maroon">c</font>, <font color="Maroon">d'</font> = <font color="Maroon">d</font> as   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="analmetr.html#K3" target="_self">Af</a> <font color="Maroon">POS</font></span>)</span> ;<br/>
<a NAME="E6:81_1_1"/>
<font color="Maroon">a'</font>,<font color="Maroon">b'</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c'</font>,<font color="Maroon">d'</font>
 
<b>by </b><i>, </i>;<br/>
<a NAME="E7:81_1_1"/><b>then </b>
<font color="Maroon">c'</font>,<font color="Maroon">d'</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">a'</font>,<font color="Maroon">b'</font>
 
<b>by </b><i><a class="ref" href="aff_1.html#T13">AFF_1:13</a></i>;<br/>
<a NAME="E8:81_1_1"/><b>then </b>
<font color="Maroon">c</font>,<font color="Maroon">d</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">a</font>,<font color="Maroon">b</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E9:81_1_1"/>
<font color="Maroon">M</font> <a href="analmetr.html#R8" target="_self">//</a> <font color="Maroon">K</font>
 <b>by </b><i>, <a class="ref" href="analmetr.html#T11" target="_self">Th11</a></i>;<br/>


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