<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="diraf.html#NM1">AffinSpace</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font>, <font color="Maroon">c<sub>5</sub></font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>









<b>assume </b><b>that </b><br/><a NAME="E1:31"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="aff_4.html#NR1" target="_self">is_plane</a> 
 <b>and </b><br/><a NAME="E2:31"/><i><font color="Green">E27</font></i>: 
( <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>4</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font> )
 <b>and </b><br/><a NAME="E3:31"/><i><font color="Green">E28</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>5</sub></font>
 <b>and </b><br/><a NAME="E4:31"/><i><font color="Green">E29</font></i>: 
( <font color="Maroon">c<sub>4</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>5</sub></font> or <font color="Maroon">c<sub>5</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>4</sub></font> )
 ;<br/>

<a NAME="E5:31"/><i><font color="Green">E30</font></i>: 
( <font color="Maroon">c<sub>4</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a>  &amp; <font color="Maroon">c<sub>5</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a>  )
 
<b>by </b><i><a class="txt" href="aff_4.html#E4:31"><i><font color="Green">E29</font></i></a>, <a class="ref" href="aff_1.html#T50">AFF_1:50</a></i>;<br/>
<b>consider </b><font color="Maroon">c<sub>6</sub></font>, <font color="Maroon">c<sub>7</sub></font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E7:31"/><i><font color="Green">E31</font></i>: 
( <font color="Maroon">c<sub>6</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a>  &amp; <font color="Maroon">c<sub>7</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a>  )
 <b>and </b><br/><a NAME="E8:31"/><i><font color="Green">E32</font></i>: 
not <font color="Maroon">c<sub>6</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>7</sub></font>
 <b>and </b><br/><a NAME="E9:31"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="aff_4.html#K1" target="_self">Plane</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E1:31"><i><font color="Green">E26</font></i></a>, <a class="ref" href="aff_4.html#D2" target="_self">Def2</a></i>;<br/>
<div><i><font color="Green">E34</font></i>: <a class="txt" onclick="hs2(this)" href="javascript:()" title="31_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:31_1"/>
<font color="Maroon">c<sub>6</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/><a NAME="E2:31_1"/><b>then </b>
<font color="Maroon">c<sub>6</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>5</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E4:31"><i><font color="Green">E29</font></i></a>, <a class="ref" href="aff_1.html#T58">AFF_1:58</a></i>;<br/><b>hence </b><a NAME="E3:31_1"/>
<font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E2:31"><i><font color="Green">E27</font></i></a>, <a class="txt" href="aff_4.html#E3:31"><i><font color="Green">E28</font></i></a>, <a class="txt" href="aff_4.html#E7:31"><i><font color="Green">E31</font></i></a>, <a class="txt" href="aff_4.html#E9:31"><i><font color="Green">E33</font></i></a>, <a class="txt" href="aff_4.html#E24"><i><font color="Green">Lemma18</font></i></a></i>;<br/></div><b>end;</b></div>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="31_2"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:31_2"/><i><font color="Green">E35</font></i>: 
not <font color="Maroon">c<sub>6</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/><a NAME="E2:31_2"/><b>then </b><i><font color="Green">E36</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="aff_4.html#K1" target="_self">Plane</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E2:31"><i><font color="Green">E27</font></i></a>, <a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="txt" href="aff_4.html#E7:31"><i><font color="Green">E31</font></i></a>, <a class="txt" href="aff_4.html#E8:31"><i><font color="Green">E32</font></i></a>, <a class="txt" href="aff_4.html#E9:31"><i><font color="Green">E33</font></i></a>, <a class="ref" href="aff_4.html#T20" target="_self">Th20</a></i>;<br/><a NAME="E3:31_2"/><i><font color="Green">E37</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a>  <a href="aff_4.html#K1" target="_self">Plane</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E2:31"><i><font color="Green">E27</font></i></a>, <a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="txt" href="aff_4.html#E7:31"><i><font color="Green">E31</font></i></a>, <a class="txt" href="aff_4.html#E8:31"><i><font color="Green">E32</font></i></a>, <a class="txt" href="aff_4.html#E9:31"><i><font color="Green">E33</font></i></a>, <a class="txt" href="aff_4.html#E1:31_2"><i><font color="Green">E35</font></i></a>, <a class="ref" href="aff_4.html#T20" target="_self">Th20</a></i>;<br/><div><a class="txt" onclick="hs2(this)" href="javascript:()" title="31_2_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:31_2_1"/><i><font color="Green">E38</font></i>: 
<font color="Maroon">c<sub>4</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>5</sub></font>
 ;<br/><b>consider </b><font color="Maroon">c<sub>8</sub></font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E3:31_2_1"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>8</sub></font> <a href="aff_1.html#R2">//</a> <font color="Maroon">c<sub>6</sub></font>
 <b>and </b><br/><a NAME="E4:31_2_1"/><i><font color="Green">E40</font></i>: 
<font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E3:31_2"><i><font color="Green">E37</font></i></a>, <a class="txt" href="aff_4.html#E17"><i><font color="Green">Lemma14</font></i></a></i>;<br/><b>consider </b><font color="Maroon">c<sub>9</sub></font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E6:31_2_1"/><i><font color="Green">E41</font></i>: 
<font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>9</sub></font>
 <b>and </b><br/><a NAME="E7:31_2_1"/><i><font color="Green">E42</font></i>: 
<font color="Maroon">c<sub>9</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="ref" href="aff_1.html#T32">AFF_1:32</a></i>;<br/><b>consider </b><font color="Maroon">c<sub>10</sub></font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E9:31_2_1"/><i><font color="Green">E43</font></i>: 
( <font color="Maroon">c<sub>8</sub></font>,<font color="Maroon">c<sub>2</sub></font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c<sub>9</sub></font>,<font color="Maroon">c<sub>10</sub></font> &amp; <font color="Maroon">c<sub>8</sub></font>,<font color="Maroon">c<sub>9</sub></font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>10</sub></font> )
 <b>by </b><i><a class="ref" href="diraf.html#T47">DIRAF:47</a></i>;<br/><a NAME="E10:31_2_1"/><i><font color="Green">E44</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>8</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E3:31"><i><font color="Green">E28</font></i></a>, <a class="txt" href="aff_4.html#E4:31"><i><font color="Green">E29</font></i></a>, <a class="txt" href="aff_4.html#E1:31_2_1"><i><font color="Green">E38</font></i></a>, <a class="txt" href="aff_4.html#E4:31_2_1"><i><font color="Green">E40</font></i></a>, <a class="ref" href="aff_1.html#T59">AFF_1:59</a></i>;<br/><a NAME="E11:31_2_1"/><i><font color="Green">E45</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>10</sub></font>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="31_2_1_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:31_2_1_1"/>
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>10</sub></font>
 ;<br/>

<a NAME="E2:31_2_1_1"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>8</sub></font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>9</sub></font>
 
<b>by </b><i><a class="txt" href="aff_4.html#E9:31_2_1"><i><font color="Green">E43</font></i></a>, <a class="ref" href="aff_1.html#T13">AFF_1:13</a></i>;<br/>
<a NAME="E3:31_2_1_1"/><b>then </b>
 <a href="aff_1.html#R1">LIN</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>8</sub></font>,<font color="Maroon">c<sub>9</sub></font>
 
<b>by </b><i><a class="ref" href="aff_1.html#D1">AFF_1:def 1</a></i>;<br/>
<a NAME="E4:31_2_1_1"/><b>then </b>
 <a href="aff_1.html#R1">LIN</a> <font color="Maroon">c<sub>8</sub></font>,<font color="Maroon">c<sub>9</sub></font>,<font color="Maroon">c<sub>2</sub></font>
 
<b>by </b><i><a class="ref" href="aff_1.html#T15">AFF_1:15</a></i>;<br/>
<a NAME="E5:31_2_1_1"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>4</sub></font>
 
<b>by </b><i><a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="txt" href="aff_4.html#E4:31_2_1"><i><font color="Green">E40</font></i></a>, <a class="txt" href="aff_4.html#E6:31_2_1"><i><font color="Green">E41</font></i></a>, <a class="txt" href="aff_4.html#E7:31_2_1"><i><font color="Green">E42</font></i></a>, <a class="ref" href="aff_1.html#T39">AFF_1:39</a></i>;<br/>
<b>hence </b><a NAME="E6:31_2_1_1"/>
contradiction
 <b>by </b><i><a class="txt" href="aff_4.html#E3:31"><i><font color="Green">E28</font></i></a>, <a class="txt" href="aff_4.html#E4:31"><i><font color="Green">E29</font></i></a>, <a class="txt" href="aff_4.html#E1:31_2_1"><i><font color="Green">E38</font></i></a>, <a class="ref" href="aff_1.html#T59">AFF_1:59</a></i>;<br/>


</div><b>end;</b></div><a NAME="E12:31_2_1"/>
<font color="Maroon">c<sub>8</sub></font>,<font color="Maroon">c<sub>9</sub></font> <a href="aff_1.html#R2">//</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="txt" href="aff_4.html#E4:31_2_1"><i><font color="Green">E40</font></i></a>, <a class="txt" href="aff_4.html#E7:31_2_1"><i><font color="Green">E42</font></i></a>, <a class="ref" href="aff_1.html#T66">AFF_1:66</a></i>;<br/><a NAME="E13:31_2_1"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>10</sub></font> <a href="aff_1.html#R2">//</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E6:31_2_1"><i><font color="Green">E41</font></i></a>, <a class="txt" href="aff_4.html#E9:31_2_1"><i><font color="Green">E43</font></i></a>, <a class="ref" href="aff_1.html#T46">AFF_1:46</a></i>;<br/><a NAME="E14:31_2_1"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>10</sub></font> <a href="aff_1.html#R2">//</a> <font color="Maroon">c<sub>5</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E4:31"><i><font color="Green">E29</font></i></a>, <a class="ref" href="aff_4.html#T3" target="_self">Th3</a></i>;<br/><a NAME="E15:31_2_1"/><b>then </b><i><font color="Green">E46</font></i>: 
<font color="Maroon">c<sub>10</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>5</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E3:31"><i><font color="Green">E28</font></i></a>, <a class="ref" href="aff_4.html#T2" target="_self">Th2</a></i>;<br/><a NAME="E16:31_2_1"/>
<font color="Maroon">c<sub>10</sub></font>,<font color="Maroon">c<sub>9</sub></font> <a href="aff_1.html#R2">//</a> <font color="Maroon">c<sub>6</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E3:31_2_1"><i><font color="Green">E39</font></i></a>, <a class="txt" href="aff_4.html#E9:31_2_1"><i><font color="Green">E43</font></i></a>, <a class="txt" href="aff_4.html#E10:31_2_1"><i><font color="Green">E44</font></i></a>, <a class="ref" href="aff_4.html#T4" target="_self">Th4</a></i>;<br/><a NAME="E17:31_2_1"/><b>then </b>
<font color="Maroon">c<sub>10</sub></font> <a href="hidden.html#R2">in</a>  <a href="aff_4.html#K1" target="_self">Plane</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E7:31_2_1"><i><font color="Green">E42</font></i></a></i>;<br/><b>hence </b><a NAME="E18:31_2_1"/>
<font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E2:31"><i><font color="Green">E27</font></i></a>, <a class="txt" href="aff_4.html#E3:31"><i><font color="Green">E28</font></i></a>, <a class="txt" href="aff_4.html#E5:31"><i><font color="Green">E30</font></i></a>, <a class="txt" href="aff_4.html#E7:31"><i><font color="Green">E31</font></i></a>, <a class="txt" href="aff_4.html#E2:31_2"><i><font color="Green">E36</font></i></a>, <a class="txt" href="aff_4.html#E11:31_2_1"><i><font color="Green">E45</font></i></a>, <a class="txt" href="aff_4.html#E15:31_2_1"><i><font color="Green">E46</font></i></a>, <a class="txt" href="aff_4.html#E25"><i><font color="Green">Lemma19</font></i></a></i>;<br/></div><b>end;</b></div><b>hence </b><a NAME="E5:31_2"/>
<font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E2:31"><i><font color="Green">E27</font></i></a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E12:31"/>
<font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E10:31"><i><font color="Green">E34</font></i></a></i>;<br/>


</div>
