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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">p</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>;<br/><b>let </b><font color="Maroon">b</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>;<br/><b>let </b><font color="Maroon">c</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font>;<br/><b>let </b><font color="Maroon">d</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="E1:18"/><i><font color="Green">E29</font></i>: 
not  <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">b</font>,<font color="Maroon">c</font>
 <b>and </b><br/><a NAME="E2:18"/><i><font color="Green">E30</font></i>: 
 <a href="diraf.html#R1">Mid</a> <font color="Maroon">b</font>,<font color="Maroon">p</font>,<font color="Maroon">a</font>
 <b>and </b><br/><a NAME="E3:18"/><i><font color="Green">E31</font></i>: 
 <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">c</font>,<font color="Maroon">d</font>
 <b>and </b><br/><a NAME="E4:18"/><i><font color="Green">E32</font></i>: 
<font color="Maroon">b</font>,<font color="Maroon">c</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">d</font>,<font color="Maroon">a</font>
 ;<br/>

<b>assume </b><a NAME="E5:18"/><i><font color="Green">E33</font></i>: 
not  <a href="diraf.html#R1">Mid</a> <font color="Maroon">c</font>,<font color="Maroon">p</font>,<font color="Maroon">d</font>
 ;<br/>

<a NAME="E6:18"/><b>then </b><i><font color="Green">E34</font></i>: 
( <font color="Maroon">d</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">p</font> &amp; <font color="Maroon">p</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c</font> )
 
<b>by </b><i><a class="ref" href="diraf.html#T14">DIRAF:14</a></i>;<br/>
<a NAME="E7:18"/>
<font color="Maroon">p</font>,<font color="Maroon">c</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#D5">DIRAF:def 5</a></i>;<br/>
<a NAME="E8:18"/><b>then </b><i><font color="Green">E35</font></i>: 
( <font color="Maroon">p</font>,<font color="Maroon">c</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">p</font>,<font color="Maroon">d</font> or <font color="Maroon">p</font>,<font color="Maroon">c</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">d</font>,<font color="Maroon">p</font> )
 
<b>by </b><i><a class="ref" href="diraf.html#D4">DIRAF:def 4</a></i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="18_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:18_1"/>
<font color="Maroon">p</font>,<font color="Maroon">c</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">d</font>,<font color="Maroon">p</font>
 ;<br/><a NAME="E2:18_1"/><b>then </b>
<font color="Maroon">c</font>,<font color="Maroon">p</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>
 <b>by </b><i><a class="ref" href="diraf.html#T5">DIRAF:5</a></i>;<br/><b>hence </b><a NAME="E3:18_1"/>
contradiction
 <b>by </b><i>, <a class="ref" href="diraf.html#D3">DIRAF:def 3</a></i>;<br/></div><b>end;</b></div>
<b>then consider </b><font color="Maroon">q</font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">OAS</font><b> such that </b><br/><a NAME="E11:18"/><i><font color="Green">E36</font></i>: 
<font color="Maroon">p</font>,<font color="Maroon">b</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">p</font>,<font color="Maroon">q</font>
 <b>and </b><br/><a NAME="E12:18"/><i><font color="Green">E37</font></i>: 
<font color="Maroon">b</font>,<font color="Maroon">c</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">d</font>,<font color="Maroon">q</font>
 <b>and </b><br/><a NAME="E13:18"/>
<font color="Maroon">d</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">q</font>
 <b>by </b><i>, , </i>;<br/>
<a NAME="E14:18"/>
<font color="Maroon">p</font>,<font color="Maroon">b</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">p</font>,<font color="Maroon">q</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#D4">DIRAF:def 4</a></i>;<br/>
<a NAME="E15:18"/><b>then </b><i><font color="Green">E38</font></i>: 
 <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">b</font>,<font color="Maroon">q</font>
 
<b>by </b><i><a class="ref" href="diraf.html#D5">DIRAF:def 5</a></i>;<br/>
<a NAME="E16:18"/>
 <a href="diraf.html#R3">LIN</a> <font color="Maroon">b</font>,<font color="Maroon">p</font>,<font color="Maroon">a</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#T34">DIRAF:34</a></i>;<br/>
<a NAME="E17:18"/><b>then </b>
 <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">b</font>,<font color="Maroon">a</font>
 
<b>by </b><i><a class="ref" href="diraf.html#T36">DIRAF:36</a></i>;<br/>
<a NAME="E18:18"/><b>then </b>
<font color="Maroon">a</font> <a href="hidden.html#R1">=</a> <font color="Maroon">q</font>
 
<b>by </b><i>, , , , , </i>;<br/>
<a NAME="E19:18"/><b>then </b>
<font color="Maroon">b</font>,<font color="Maroon">p</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">p</font>,<font color="Maroon">q</font>
 
<b>by </b><i>, <a class="ref" href="diraf.html#D3">DIRAF:def 3</a></i>;<br/>
<a NAME="E20:18"/><b>then </b>
<font color="Maroon">p</font>,<font color="Maroon">q</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">b</font>,<font color="Maroon">p</font>
 
<b>by </b><i><a class="ref" href="diraf.html#T5">DIRAF:5</a></i>;<br/>
<a NAME="E21:18"/><b>then </b>
( <font color="Maroon">p</font>,<font color="Maroon">b</font> <a href="analoaf.html#R2">//</a> <font color="Maroon">b</font>,<font color="Maroon">p</font> or <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <font color="Maroon">q</font> )
 
<b>by </b><i>, <a class="ref" href="diraf.html#T6">DIRAF:6</a></i>;<br/>
<a NAME="E22:18"/><b>then </b>
( <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <font color="Maroon">b</font> or <font color="Maroon">p</font> <a href="hidden.html#R1">=</a> <font color="Maroon">q</font> )
 
<b>by </b><i><a class="ref" href="analoaf.html#D5">ANALOAF:def 5</a></i>;<br/>
<a NAME="E23:18"/><b>then </b>
(  <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>,<font color="Maroon">c</font> &amp; <font color="Maroon">p</font>,<font color="Maroon">d</font> <a href="diraf.html#R2">'||'</a> <font color="Maroon">c</font>,<font color="Maroon">b</font> )
 
<b>by </b><i>, , , <a class="ref" href="diraf.html#T27">DIRAF:27</a>, <a class="ref" href="diraf.html#T36">DIRAF:36</a>, <a class="ref" href="diraf.html#T37">DIRAF:37</a></i>;<br/>
<a NAME="E24:18"/><b>then </b>
(  <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>,<font color="Maroon">p</font> &amp;  <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>,<font color="Maroon">c</font> &amp;  <a href="diraf.html#R3">LIN</a> <font color="Maroon">p</font>,<font color="Maroon">d</font>,<font color="Maroon">b</font> )
 
<b>by </b><i>, <a class="ref" href="diraf.html#T37">DIRAF:37</a>, <a class="ref" href="diraf.html#T39">DIRAF:39</a></i>;<br/>
<b>hence </b><a NAME="E25:18"/>
contradiction
 <b>by </b><i>, , <a class="ref" href="diraf.html#T38">DIRAF:38</a></i>;<br/>


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