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<b>let </b><font color="Maroon">x0</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y0</font> be   <a href="real_1.html#NM1">Real</a>;<br/><b>let </b><font color="Maroon">P</font> be   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span>;<br/>



<b>assume </b><a NAME="E1:61"/><i><font color="Green">E28</font></i>: 
<font color="Maroon">P</font> <a href="hidden.html#R1">=</a> <span class="p1">{<span class="default"> <span class="p2"><a href="euclid.html#K23">|[</a><span class="default"><font color="Maroon">x0</font>,<font color="Olive">y</font></span><a href="euclid.html#K23">]|</a></span> where <font color="Olive">y</font> is   <a href="real_1.html#NM1">Real</a> : <font color="Olive">y</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">y0</font> </span>}</span> 
 ;<br/>

<b>let </b><font color="Maroon">w1</font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span>, <font color="Maroon">w2</font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span>; <i><font color="Red">:: according to </font></i><a class="ref" href="jordan1.html#D1" target="_self">JORDAN1:def 1</a><br/>

<b>assume </b><b>that </b><br/><a NAME="E2:61"/><i><font color="Green">E30</font></i>: 
<font color="Maroon">w1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">P</font>
 <b>and </b><br/><a NAME="E3:61"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">w2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">P</font>
 ;<br/>

<b>consider </b><font color="Maroon">y1</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><br/><a NAME="E5:61"/><i><font color="Green">E32</font></i>: 
<font color="Maroon">w1</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><font color="Maroon">x0</font>,<font color="Maroon">y1</font></span><a href="euclid.html#K23">]|</a></span>
 <b>and </b><br/><a NAME="E6:61"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">y1</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">y0</font>
 <b>by </b><i>, </i>;<br/>
<b>consider </b><font color="Maroon">y2</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><br/><a NAME="E8:61"/><i><font color="Green">E34</font></i>: 
<font color="Maroon">w2</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><font color="Maroon">x0</font>,<font color="Maroon">y2</font></span><a href="euclid.html#K23">]|</a></span>
 <b>and </b><br/><a NAME="E9:61"/><i><font color="Green">E37</font></i>: 
<font color="Maroon">y2</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">y0</font>
 <b>by </b><i>, </i>;<br/>
<b>let </b><font color="Maroon">v</font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a><br/>

<b>assume </b><a NAME="E10:61"/><i><font color="Green">E38</font></i>: 
<font color="Maroon">v</font> <a href="hidden.html#R2">in</a>  <a href="topreal1.html#K3">LSeg</a> <font color="Maroon">w1</font>,<font color="Maroon">w2</font>
 ;<br/>

<b>then reconsider </b><font color="Maroon">v1</font> = <font color="Maroon">v</font> as   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> ;<br/>
<a NAME="E12:61"/>
<font color="Maroon">v1</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><span class="p3">(<span class="default"><span class="p4">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Olive">l</font></span>)</span> <a href="euclid.html#K18">*</a> <font color="Maroon">w1</font></span>)</span> <a href="euclid.html#K17">+</a> <span class="p3">(<span class="default"><font color="Olive">l</font> <a href="euclid.html#K18">*</a> <font color="Maroon">w2</font></span>)</span></span>)</span> where <font color="Olive">l</font> is   <a href="real_1.html#NM1">Real</a> : ( 0 <a href="xxreal_0.html#R1">&lt;=</a> <font color="Olive">l</font> &amp; <font color="Olive">l</font> <a href="xxreal_0.html#R1">&lt;=</a> 1 ) </span>}</span> 
 
<b>by </b><i><a class="ref" href="jordan1.html#T8" target="_self">Th8</a>, <a class="ref" href="topreal1.html#D3">TOPREAL1:def 3</a></i>;<br/>
<b>then consider </b><font color="Maroon">l</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><br/><a NAME="E14:61"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">v1</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="euclid.html#K18">*</a> <font color="Maroon">w1</font></span>)</span> <a href="euclid.html#K17">+</a> <span class="p1">(<span class="default"><font color="Maroon">l</font> <a href="euclid.html#K18">*</a> <font color="Maroon">w2</font></span>)</span>
 <b>and </b><br/><a NAME="E15:61"/><i><font color="Green">E40</font></i>: 
0 <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">l</font>
 <b>and </b><br/><a NAME="E16:61"/><i><font color="Green">E41</font></i>: 
<font color="Maroon">l</font> <a href="xxreal_0.html#R1">&lt;=</a> 1
 ;<br/>
<i><font color="Green">E42</font></i>: <font color="Maroon">v1</font> = 
<span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">y1</font></span>)</span></span><a href="euclid.html#K23">]|</a></span> <a href="euclid.html#K17">+</a> <span class="p1">(<span class="default"><font color="Maroon">l</font> <a href="euclid.html#K18">*</a> <span class="p2"><a href="euclid.html#K23">|[</a><span class="default"><font color="Maroon">x0</font>,<font color="Maroon">y2</font></span><a href="euclid.html#K23">]|</a></span></span>)</span>
<b>by </b><i>, , , <a class="ref" href="euclid.html#T62">EUCLID:62</a></i>
<br/>.= 
<span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">y1</font></span>)</span></span><a href="euclid.html#K23">]|</a></span> <a href="euclid.html#K17">+</a> <span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span>,<span class="p2">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">y2</font></span>)</span></span><a href="euclid.html#K23">]|</a></span>
<b>by </b><i><a class="ref" href="euclid.html#T62">EUCLID:62</a></i>
<br/>.= 
<span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><span class="p4">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p3">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default"><span class="p4">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">y1</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p3">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">y2</font></span>)</span></span>)</span></span><a href="euclid.html#K23">]|</a></span>
<b>by </b><i><a class="ref" href="euclid.html#T60">EUCLID:60</a></i>
<br/>.= 
<span class="p1"><a href="euclid.html#K23">|[</a><span class="default"><span class="p2">(<span class="default">1 <a href="real_1.html#K4">*</a> <font color="Maroon">x0</font></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default"><span class="p4">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">y1</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p3">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">y2</font></span>)</span></span>)</span></span><a href="euclid.html#K23">]|</a></span>

;<br/>
<a NAME="E18:61"/>
<span class="p1">(<span class="default"><span class="p2">(<span class="default">1 <a href="real_1.html#K5">-</a> <font color="Maroon">l</font></span>)</span> <a href="real_1.html#K4">*</a> <font color="Maroon">y1</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><font color="Maroon">l</font> <a href="real_1.html#K4">*</a> <font color="Maroon">y2</font></span>)</span> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">y0</font>
 
<b>by </b><i><a class="ref" href="jordan1.html#T6" target="_self">Th6</a>, <a class="ref" href="jordan1.html#T7" target="_self">Th7</a>, , , <a class="ref" href="xreal_1.html#T176">XREAL_1:176</a></i>;<br/>
<b>hence </b><a NAME="E19:61"/>
<font color="Maroon">v</font> <a href="hidden.html#R2">in</a> <font color="Maroon">P</font>
 <b>by </b><i>, </i>;<br/>


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