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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="diraf.html#NM2">AffinPlane</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</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>4</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="E1:70"/><i><font color="Green">E54</font></i>: 
<font color="Maroon">c<sub>4</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a> 
 <b>and </b><br/><a NAME="E2:70"/><i><font color="Green">E55</font></i>: 
not <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#R2" target="_self">//</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<a NAME="E3:70"/><i><font color="Green">E56</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>3</sub></font>
 
<b>by </b><i><a class="txt" href="aff_1.html#E1:70"><i><font color="Green">E54</font></i></a>, <a class="txt" href="aff_1.html#E2:70"><i><font color="Green">E55</font></i></a>, <a class="ref" href="aff_1.html#T47" target="_self">Th47</a></i>;<br/>
<b>set </b><font color="Maroon">c<sub>5</sub></font> =  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>;<br/>
<a NAME="E4:70"/><i><font color="Green">E57</font></i>: 
 <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a> 
 
<b>by </b><i><a class="txt" href="aff_1.html#E3:70"><i><font color="Green">E56</font></i></a>, <a class="ref" href="aff_1.html#D3" target="_self">Def3</a></i>;<br/>
<a NAME="E5:70"/>
not  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#R4" target="_self">//</a> <font color="Maroon">c<sub>4</sub></font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="70_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:70_1"/>
 <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#R4" target="_self">//</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<b>then consider </b><font color="Maroon">c<sub>6</sub></font>, <font color="Maroon">c<sub>7</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="E3:70_1"/><i><font color="Green">E58</font></i>: 
(  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font> &amp; <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>7</sub></font> &amp; <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font> <a href="aff_1.html#R2" target="_self">//</a> <font color="Maroon">c<sub>4</sub></font> )
 <b>by </b><i><a class="ref" href="aff_1.html#D5" target="_self">Def5</a></i>;<br/>
<a NAME="E4:70_1"/>
( <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a>  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R2">in</a>  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> )
 
<b>by </b><i><a class="ref" href="aff_1.html#T26" target="_self">Th26</a></i>;<br/>
<a NAME="E5:70_1"/><b>then </b>
<font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font> <a href="analoaf.html#R2">//</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>
 
<b>by </b><i><a class="txt" href="aff_1.html#E3:70_1"><i><font color="Green">E58</font></i></a>, <a class="ref" href="aff_1.html#T36" target="_self">Th36</a></i>;<br/>
<b>hence </b><a NAME="E6:70_1"/>
contradiction
 <b>by </b><i><a class="txt" href="aff_1.html#E2:70"><i><font color="Green">E55</font></i></a>, <a class="txt" href="aff_1.html#E3:70_1"><i><font color="Green">E58</font></i></a>, <a class="ref" href="aff_1.html#T46" target="_self">Th46</a></i>;<br/>


</div><b>end;</b></div>
<b>then consider </b><font color="Maroon">c<sub>6</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="E7:70"/><i><font color="Green">E58</font></i>: 
( <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#R2">in</a>  <a href="aff_1.html#K2" target="_self">Line</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>6</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_1.html#E1:70"><i><font color="Green">E54</font></i></a>, <a class="txt" href="aff_1.html#E4:70"><i><font color="Green">E57</font></i></a>, <a class="ref" href="aff_1.html#T72" target="_self">Th72</a></i>;<br/>
<a NAME="E8:70"/>
 <a href="aff_1.html#R1" target="_self">LIN</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>6</sub></font>
 
<b>by </b><i><a class="txt" href="aff_1.html#E7:70"><i><font color="Green">E58</font></i></a>, <a class="ref" href="aff_1.html#D2" target="_self">Def2</a></i>;<br/>
<b>hence </b><a NAME="E9:70"/>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font> st <br/>( <font color="Olive">b<sub>1</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>4</sub></font> &amp;  <a href="aff_1.html#R1" target="_self">LIN</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>,<font color="Olive">b<sub>1</sub></font> )
 <b>by </b><i><a class="txt" href="aff_1.html#E7:70"><i><font color="Green">E58</font></i></a></i>;<br/>


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