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<b>let </b><font color="Maroon">OAS</font> be   <a href="analoaf.html#NM1">OAffinSpace</a>;<br/><b>let </b><font color="Maroon">o</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>, <font color="Maroon">a</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>, <font color="Maroon">b</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>, <font color="Maroon">a'</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>, <font color="Maroon">b'</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>;<br/>



<b>assume </b><b>that </b><br/><a NAME="E1:20"/><i><font color="Green">E28</font></i>: 
not  <a href="diraf.html#R3">LIN</a> <font color="Maroon">o</font>,<font color="Maroon">a</font>,<font color="Maroon">b</font>
 <b>and </b><br/><a NAME="E2:20"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">a</font>,<font color="Maroon">o</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">o</font>,<font color="Maroon">a'</font>
 <b>and </b><br/><a NAME="E3:20"/><i><font color="Green">E38</font></i>: 
 <a href="diraf.html#R3">LIN</a> <font color="Maroon">o</font>,<font color="Maroon">b</font>,<font color="Maroon">b'</font>
 <b>and </b><br/><a NAME="E4:20"/><i><font color="Green">E43</font></i>: 
<font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">a'</font>,<font color="Maroon">b'</font>
 ;<br/>

<a NAME="E5:20"/><i><font color="Green">E59</font></i>: 
 <a href="diraf.html#R1">Mid</a> <font color="Maroon">a</font>,<font color="Maroon">o</font>,<font color="Maroon">a'</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#D3">DIRAF:def 3</a></i>;<br/>
<a NAME="E6:20"/>
<font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">b'</font>,<font color="Maroon">a'</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#T27">DIRAF:27</a></i>;<br/>
<a NAME="E7:20"/><b>then </b>
 <a href="diraf.html#R1">Mid</a> <font color="Maroon">b</font>,<font color="Maroon">o</font>,<font color="Maroon">b'</font>
 
<b>by </b><i>, , , <a class="ref" href="pasch.html#T13">PASCH:13</a></i>;<br/>
<b>hence </b><a NAME="E8:20"/>
<font color="Maroon">b</font>,<font color="Maroon">o</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">o</font>,<font color="Maroon">b'</font>
 <b>by </b><i><a class="ref" href="diraf.html#D3">DIRAF:def 3</a></i>;<br/>

<b>hence </b><a NAME="E9:20"/>
<font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">b'</font>,<font color="Maroon">a'</font>
 <b>by </b><i>, , , <a class="ref" href="pasch.html#T19">PASCH:19</a></i>;<br/>


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