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<b>let </b><font color="Maroon" title="c1">AS</font> be   <a href="diraf.html#NM1" title="DIRAF:NM.1">AffinSpace</a>;<br/><b>let </b><font color="Maroon" title="c2">a</font> be   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">AS</font>;<br/><b>let </b><font color="Maroon" title="c3">X</font>, <font color="Maroon" title="c4">Y</font> be   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c1">AS</font>;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:88"/><i><font color="Green" title="E69">A1</font></i>: 
( <font color="Maroon" title="c3">X</font> <a href="aff_4.html#NR1" title="AFF_4:NR.1">is_plane</a>  &amp; <font color="Maroon" title="c4">Y</font> <a href="aff_4.html#NR1" title="AFF_4:NR.1">is_plane</a>  )
 <b>and </b><br/><a NAME="E2:88"/><i><font color="Green" title="E70">A2</font></i>: 
<font color="Maroon" title="c3">X</font> <a href="aff_4.html#R1" title="AFF_4:pred.1">'||'</a> <font color="Maroon" title="c4">Y</font>
 ;<br/>

<a NAME="E3:88"/><i><font color="Green" title="E71">A3</font></i>: 
( <font color="Maroon" title="c2">a</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> &amp; <font color="Maroon" title="c2">a</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c4">Y</font> &amp; <font color="Maroon" title="c3">X</font> <a href="aff_4.html#R1" title="AFF_4:pred.1">'||'</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> &amp; <font color="Maroon" title="c4">Y</font> <a href="aff_4.html#R1" title="AFF_4:pred.1">'||'</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c4">Y</font> &amp; <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> <a href="aff_4.html#NR1" title="AFF_4:NR.1">is_plane</a>  &amp; <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c4">Y</font> <a href="aff_4.html#NR1" title="AFF_4:NR.1">is_plane</a>  )
 
<b>by </b><i><a class="txt" href="aff_4.html#E1:88"><i><font color="Green" title="E69">A1</font></i></a>, <a class="ref" href="aff_4.html#D6" target="_self" title="AFF_4:def.6">Def6</a></i>;<br/>
<a NAME="E4:88"/><b>then </b>
<font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> <a href="aff_4.html#R1" title="AFF_4:pred.1">'||'</a> <font color="Maroon" title="c4">Y</font>
 
<b>by </b><i><a class="txt" href="aff_4.html#E1:88"><i><font color="Green" title="E69">A1</font></i></a>, <a class="txt" href="aff_4.html#E2:88"><i><font color="Green" title="E70">A2</font></i></a>, <a class="ref" href="aff_4.html#T61" target="_self" title="AFF_4:th.61">Th61</a></i>;<br/>
<a NAME="E5:88"/><b>then </b>
<font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> <a href="aff_4.html#R1" title="AFF_4:pred.1">'||'</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c4">Y</font>
 
<b>by </b><i><a class="txt" href="aff_4.html#E1:88"><i><font color="Green" title="E69">A1</font></i></a>, <a class="txt" href="aff_4.html#E3:88"><i><font color="Green" title="E71">A3</font></i></a>, <a class="ref" href="aff_4.html#T61" target="_self" title="AFF_4:th.61">Th61</a></i>;<br/>
<b>hence </b><a NAME="E6:88"/>
<font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c3">X</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">a</font> <a href="aff_4.html#K3" title="AFF_4:func.3">+</a> <font color="Maroon" title="c4">Y</font>
 <b>by </b><i><a class="txt" href="aff_4.html#E3:88"><i><font color="Green" title="E71">A3</font></i></a>, <a class="txt" href="aff_4.html#E80"><i><font color="Green" title="E65">Lm14</font></i></a></i>;<br/>


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