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<b>let </b><font color="Maroon">AS</font> be   <a href="diraf.html#NM1">AffinSpace</a>;<br/><b>let </b><font color="Maroon">X</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">AS</font>;<br/><b>let </b><font color="Maroon">A</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">AS</font>;<br/><b>let </b><font color="Maroon">Y</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">AS</font>;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:6"/><i><font color="Green">E25</font></i>: 
<font color="Maroon">X</font> <a href="aff_4.html#NR1" target="_self">is_plane</a> 
 <b>and </b><br/><a NAME="E2:6"/><i><font color="Green">E26</font></i>: 
( <font color="Maroon">A</font> <a href="aff_4.html#R1">'||'</a> <font color="Maroon">X</font> &amp; <font color="Maroon">X</font> <a href="aff_4.html#R1">'||'</a> <font color="Maroon">Y</font> )
 ;<br/>

<a NAME="E3:6"/>
<font color="Maroon">X</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i>, <a class="ref" href="aff_4.html#T59">AFF_4:59</a></i>;<br/>
<b>hence </b><a NAME="E4:6"/>
<font color="Maroon">A</font> <a href="aff_4.html#R1">'||'</a> <font color="Maroon">Y</font>
 <b>by </b><i>, <a class="ref" href="aff_4.html#T60">AFF_4:60</a></i>;<br/>


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