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

<b>let </b><font color="Maroon">D</font> be   <a href="topreal2.html#NM1">Simple_closed_curve</a>;<br/><b>let </b><font color="Maroon">C</font> be  <a href="pre_topc.html#V4">closed</a> <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="E1:89"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 ;<br/>

<a NAME="E2:89"/>
<font color="Maroon">D</font> is <a href="jordan2c.html#V1">Bounded</a>
 
<b>by </b><i><a class="ref" href="jordan2c.html#T73">JORDAN2C:73</a></i>;<br/>
<a NAME="E3:89"/><b>then </b>
<font color="Maroon">C</font> is <a href="jordan2c.html#V1">Bounded</a>
 
<b>by </b><i>, <a class="ref" href="jordan2c.html#T16">JORDAN2C:16</a></i>;<br/>
<a NAME="E4:89"/><b>then </b><i><font color="Green">E32</font></i>: 
<font color="Maroon">C</font> is <a href="compts_1.html#V6">compact</a>
 
<b>by </b><i><a class="ref" href="topreal6.html#T88">TOPREAL6:88</a></i>;<br/>
<b>assume </b><a NAME="E5:89"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">C</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">D</font>
 ;<br/>

<a NAME="E6:89"/><i><font color="Green">E47</font></i>: 
for <font color="Olive">C</font> being <a href="compts_1.html#V6">compact</a> <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>  st not <font color="Olive">C</font> is <a href="realset1.html#V1">trivial</a> &amp; <font color="Olive">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> &amp; <font color="Olive">C</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">D</font> holds <br/> ex <font color="Olive">p1</font>, <font color="Olive">p2</font> being  <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> ex <font color="Olive">B</font> being  <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> st <br/>( <font color="Olive">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Olive">p1</font>,<font color="Olive">p2</font> &amp; <font color="Olive">C</font> <a href="tarski.html#R1">c=</a> <font color="Olive">B</font> &amp; <font color="Olive">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> )
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="89_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">C</font> be  <a href="compts_1.html#V6">compact</a> <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="E1:89_1"/>
not <font color="Maroon">C</font> is <a href="realset1.html#V1">trivial</a>
 ;<br/>

<b>then consider </b><font color="Maroon">d1</font> being   <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">d2</font> being   <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><b> such that </b><br/><a NAME="E3:89_1"/><i><font color="Green">E50</font></i>: 
( <font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font> &amp; <font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font> &amp; <font color="Maroon">d1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">d2</font> )
 <b>by </b><i><a class="ref" href="realset1.html#T15">REALSET1:15</a></i>;<br/>
<b>assume </b><a NAME="E4:89_1"/><i><font color="Green">E51</font></i>: 
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 ;<br/>

<b>assume </b><a NAME="E5:89_1"/><i><font color="Green">E52</font></i>: 
<font color="Maroon">C</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">D</font>
 ;<br/>

<a NAME="E6:89_1"/>
<font color="Maroon">C</font> <a href="xboole_0.html#R2">c&lt;</a> <font color="Maroon">D</font>
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E42:89_1"><i><font color="Green">E80</font></i></a>, <a class="txt" href="borsuk_4.html#E47:89_1"><i><font color="Green">E81</font></i></a>, <a class="ref" href="xboole_0.html#D8">XBOOLE_0:def 8</a></i>;<br/>
<b>then consider </b><font color="Maroon">p</font> being   <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><b> such that </b><br/><a NAME="E8:89_1"/><i><font color="Green">E53</font></i>: 
( <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font> &amp; <font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">p</font></span><a href="domain_1.html#K6">}</a></span> )
 <b>by </b><i>, <a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a></i>;<br/>
<a NAME="E9:89_1"/><i><font color="Green">E57</font></i>: 
( <font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">p</font></span><a href="domain_1.html#K6">}</a></span> &amp; <font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">p</font></span><a href="domain_1.html#K6">}</a></span> )
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a>, <a class="txt" href="borsuk_4.html#E49:89_1"><i><font color="Green">E82</font></i></a></i>;<br/>
<b>reconsider </b><font color="Maroon">Dp</font> = <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">p</font></span><a href="domain_1.html#K6">}</a></span> as  non <a href="xboole_0.html#V1">empty</a> <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> <b>by </b><i><a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a>, <a class="txt" href="borsuk_4.html#E49:89_1"><i><font color="Green">E82</font></i></a></i>;<br/>
<a NAME="E11:89_1"/>
<span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font>, <a href="borsuk_4.html#K1" target="_self">I(01)</a>  <a href="borsuk_3.html#R2">are_homeomorphic</a> 
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E49:89_1"><i><font color="Green">E82</font></i></a>, <a class="txt" href="borsuk_4.html#E28:89_1"><i><font color="Green">E69</font></i></a></i>;<br/>
<b>then consider </b><font color="Maroon">f</font> being   <a href="struct_0.html#NM6">Function</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>,<a href="borsuk_4.html#K1" target="_self">I(01)</a> <b> such that </b><br/><a NAME="E13:89_1"/><i><font color="Green">E58</font></i>: 
<font color="Maroon">f</font> <a href="tops_2.html#NR1" target="_self">is_homeomorphism</a> 
 <b>by </b><i><a class="ref" href="t_0topsp.html#D1">T_0TOPSP:def 1</a></i>;<br/>
<a NAME="E14:89_1"/><i><font color="Green">E59</font></i>: 
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E49:89_1"><i><font color="Green">E82</font></i></a>, <a class="ref" href="pre_topc.html#T29">PRE_TOPC:29</a></i>;<br/>
<b>reconsider </b><font color="Maroon">C'</font> = <font color="Maroon">C</font> as   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span> <b>by </b><i><a class="txt" href="borsuk_4.html#E49:89_1"><i><font color="Green">E82</font></i></a>, <a class="ref" href="pre_topc.html#T29">PRE_TOPC:29</a></i>;<br/>
<b>set </b><font color="Maroon">fC</font> = <font color="Maroon">f</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">C'</font>;<br/>
<a NAME="E16:89_1"/>
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a>  <a href="pre_topc.html#K2">[#]</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i/>;<br/>
<a NAME="E17:89_1"/><b>then </b><i><font color="Green">E60</font></i>: 
<font color="Maroon">C'</font> is <a href="compts_1.html#V6">compact</a>
 
<b>by </b><i><a class="ref" href="compts_1.html#T11">COMPTS_1:11</a></i>;<br/>
<a NAME="E18:89_1"/><i><font color="Green">E61</font></i>: 
<font color="Maroon">f</font> is <a href="pre_topc.html#V5">continuous</a>
 
<b>by </b><i>, <a class="ref" href="tops_2.html#D5">TOPS_2:def 5</a></i>;<br/>
<a NAME="E19:89_1"/><i><font color="Green">E62</font></i>: 
 <a href="relset_1.html#K5">rng</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a>  <a href="pre_topc.html#K2">[#]</a> <a href="borsuk_4.html#K1" target="_self">I(01)</a> 
 
<b>by </b><i>, <a class="ref" href="tops_2.html#D5">TOPS_2:def 5</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">fC</font> = <font color="Maroon">f</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">C'</font> as  <a href="compts_1.html#V6">compact</a> <a href="struct_0.html#NM2">Subset</a> of <a href="borsuk_4.html#K1" target="_self">I(01)</a>  <b>by </b><i>, , <a class="ref" href="compts_1.html#T24">COMPTS_1:24</a></i>;<br/>
<b>reconsider </b><font color="Maroon">fC'</font> = <font color="Maroon">fC</font> as   <a href="struct_0.html#NM2">Subset</a> of <a href="topmetr.html#K5">I[01]</a>  <b>by </b><i><a class="ref" href="pre_topc.html#T39">PRE_TOPC:39</a></i>;<br/>
<a NAME="E22:89_1"/><i><font color="Green">E63</font></i>: 
<font color="Maroon">fC'</font> <a href="tarski.html#R1">c=</a> the <a href="struct_0.html#U1">carrier</a> of <a href="borsuk_4.html#K1" target="_self">I(01)</a> 
 
;<br/>
<a NAME="E23:89_1"/><i><font color="Green">E64</font></i>: 
<font color="Maroon">fC'</font> <a href="tarski.html#R1">c=</a>  <a href="pre_topc.html#K2">[#]</a> <a href="borsuk_4.html#K1" target="_self">I(01)</a> 
 
;<br/>
<a NAME="E24:89_1"/><i><font color="Green">E65</font></i>: 
<font color="Maroon">fC'</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="rcomp_1.html#K2">].</a><span class="default">0,1</span><a href="rcomp_1.html#K2">.[</a></span>
 
<b>by </b><i>, <a class="txt" href="borsuk_4.html#E4:89_1"><i><font color="Green">E51</font></i></a></i>;<br/>
<a NAME="E25:89_1"/><i><font color="Green">E66</font></i>: 
for <font color="Olive">P</font> being  <a href="struct_0.html#NM2">Subset</a> of <a href="borsuk_4.html#K1" target="_self">I(01)</a>   st <font color="Olive">P</font> <a href="hidden.html#R1">=</a> <font color="Maroon">fC'</font> holds <br/><font color="Olive">P</font> is <a href="compts_1.html#V6">compact</a>
 
;<br/>
<a NAME="E26:89_1"/><i><font color="Green">E67</font></i>: 
<font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T7" target="_self">Th7</a>, <a class="ref" href="pre_topc.html#T29">PRE_TOPC:29</a></i>;<br/>
<a NAME="E27:89_1"/><i><font color="Green">E68</font></i>: 
<font color="Maroon">f</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">d1</font> <a href="hidden.html#R2">in</a> <font color="Maroon">f</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">C'</font>
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a>, <a class="ref" href="funct_2.html#T43">FUNCT_2:43</a></i>;<br/>
<a NAME="E28:89_1"/><i><font color="Green">E69</font></i>: 
<font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T7" target="_self">Th7</a>, <a class="ref" href="pre_topc.html#T29">PRE_TOPC:29</a></i>;<br/>
<a NAME="E29:89_1"/><i><font color="Green">E70</font></i>: 
<font color="Maroon">f</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">d2</font> <a href="hidden.html#R2">in</a> <font color="Maroon">f</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">C'</font>
 
<b>by </b><i><a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a>, <a class="ref" href="funct_2.html#T43">FUNCT_2:43</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">fC'</font> = <font color="Maroon">fC'</font> as  non <a href="xboole_0.html#V1">empty</a> <a href="compts_1.html#V6">compact</a> <a href="struct_0.html#NM2">Subset</a> of <a href="topmetr.html#K5">I[01]</a>  <b>by </b><i>, <a class="ref" href="borsuk_4.html#T10" target="_self">Th10</a>, <a class="ref" href="compts_1.html#T11">COMPTS_1:11</a></i>;<br/>
<a NAME="E31:89_1"/><i><font color="Green">E71</font></i>: 
<font color="Maroon">d1</font> <a href="hidden.html#R2">in</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T11" target="_self">Th11</a>, <a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<a NAME="E32:89_1"/><i><font color="Green">E72</font></i>: 
<font color="Maroon">d2</font> <a href="hidden.html#R2">in</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font>
 
<b>by </b><i>, <a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<b>consider </b><font color="Maroon">p1</font> being   <a href="pre_topc.html#NM2">Point</a> of <a href="topmetr.html#K5">I[01]</a> , <font color="Maroon">p2</font> being   <a href="pre_topc.html#NM2">Point</a> of <a href="topmetr.html#K5">I[01]</a> <b> such that </b><br/><a NAME="E34:89_1"/><i><font color="Green">E73</font></i>: 
( <font color="Maroon">p1</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">p2</font> &amp; <font color="Maroon">fC'</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="rcomp_1.html#K1">[.</a><span class="default"><font color="Maroon">p1</font>,<font color="Maroon">p2</font></span><a href="rcomp_1.html#K1">.]</a></span> &amp; <span class="p1"><a href="rcomp_1.html#K1">[.</a><span class="default"><font color="Maroon">p1</font>,<font color="Maroon">p2</font></span><a href="rcomp_1.html#K1">.]</a></span> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="rcomp_1.html#K2">].</a><span class="default">0,1</span><a href="rcomp_1.html#K2">.[</a></span> )
 <b>by </b><i><a class="txt" href="borsuk_4.html#E36:89_1"><i><font color="Green">E74</font></i></a>, </i>;<br/>
<b>reconsider </b><font color="Maroon">E</font> = <span class="p1"><a href="rcomp_1.html#K1">[.</a><span class="default"><font color="Maroon">p1</font>,<font color="Maroon">p2</font></span><a href="rcomp_1.html#K1">.]</a></span> as  non <a href="xboole_0.html#V1">empty</a> <a href="connsp_1.html#V2">connected</a> <a href="compts_1.html#V6">compact</a> <a href="struct_0.html#NM2">Subset</a> of <a href="topmetr.html#K5">I[01]</a>  <b>by </b><i><a class="ref" href="borsuk_4.html#T12" target="_self">Th12</a>, </i>;<br/>
<a NAME="E36:89_1"/><i><font color="Green">E74</font></i>: 
<font color="Maroon">f</font> is <a href="funct_1.html#V2">one-to-one</a>
 
<b>by </b><i>, <a class="ref" href="tops_2.html#D5">TOPS_2:def 5</a></i>;<br/>
<a NAME="E37:89_1"/>
<font color="Maroon">p1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">p2</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="89_1_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:89_1_1"/>
<font color="Maroon">p1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">p2</font>
 ;<br/>

<a NAME="E2:89_1_1"/><b>then </b><i><font color="Green">E75</font></i>: 
<font color="Maroon">fC'</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="seq_4.html#K1">{</a><span class="default"><font color="Maroon">p1</font></span><a href="seq_4.html#K1">}</a></span>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T12" target="_self">Th12</a>, <a class="ref" href="rcomp_1.html#T14">RCOMP_1:14</a></i>;<br/>
<a NAME="E3:89_1_1"/><b>then </b><i><font color="Green">E76</font></i>: 
<font color="Maroon">f</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">d1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">p1</font>
 
<b>by </b><i>, <a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<a NAME="E4:89_1_1"/>
<font color="Maroon">f</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">d2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">p1</font>
 
<b>by </b><i>, <a class="ref" href="borsuk_4.html#T15" target="_self">Th15</a>, <a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<b>hence </b><a NAME="E5:89_1_1"/>
contradiction
 <b>by </b><i><a class="txt" href="borsuk_4.html#E41:89_1"><i><font color="Green">E79</font></i></a>, , , <a class="ref" href="borsuk_4.html#T13" target="_self">Th13</a>, , <a class="ref" href="funct_1.html#D8">FUNCT_1:def 8</a></i>;<br/>


</div><b>end;</b></div>
<a NAME="E38:89_1"/><b>then </b><i><font color="Green">E77</font></i>: 
<font color="Maroon">p1</font> <a href="xxreal_0.html#NR3" target="_self">&lt;</a> <font color="Maroon">p2</font>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T12" target="_self">Th12</a>, <a class="ref" href="real_1.html#D5">REAL_1:def 5</a></i>;<br/>
<a NAME="E39:89_1"/>
 <a href="relset_1.html#K5">rng</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="rcomp_1.html#K2">].</a><span class="default">0,1</span><a href="rcomp_1.html#K2">.[</a></span>
 
<b>by </b><i>, <a class="txt" href="borsuk_4.html#E4:89_1"><i><font color="Green">E51</font></i></a></i>;<br/>
<a NAME="E40:89_1"/><b>then </b><i><font color="Green">E78</font></i>: 
<font color="Maroon">E</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K5">rng</a> <font color="Maroon">f</font>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T12" target="_self">Th12</a></i>;<br/>
<a NAME="E41:89_1"/><b>then </b><i><font color="Green">E79</font></i>: 
<font color="Maroon">f</font> <a href="relset_1.html#K11">"</a> <font color="Maroon">E</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="relat_1.html#T174">RELAT_1:174</a></i>;<br/>
<a NAME="E42:89_1"/><i><font color="Green">E80</font></i>: 
<font color="Maroon">f</font> <a href="relset_1.html#K11">"</a> <font color="Maroon">E</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font>
 
<b>by </b><i><a class="ref" href="relat_1.html#T167">RELAT_1:167</a></i>;<br/>
<a NAME="E43:89_1"/>
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i><a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<a NAME="E44:89_1"/><b>then </b>
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="tarski.html#R1">c=</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span>
 
<b>by </b><i><a class="ref" href="borsuk_1.html#T35">BORSUK_1:35</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">B</font> = <font color="Maroon">f</font> <a href="relset_1.html#K11">"</a> <font color="Maroon">E</font> as  non <a href="xboole_0.html#V1">empty</a> <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> <b>by </b><i>, <a class="ref" href="borsuk_4.html#T17" target="_self">Th17</a>, <a class="ref" href="xboole_1.html#T1">XBOOLE_1:1</a></i>;<br/>
<a NAME="E46:89_1"/>
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> the <a href="struct_0.html#U1">carrier</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">Dp</font></span>)</span>
 
<b>by </b><i><a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<a NAME="E47:89_1"/><b>then </b><i><font color="Green">E81</font></i>: 
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <font color="Maroon">Dp</font>
 
<b>by </b><i><a class="ref" href="pre_topc.html#T29">PRE_TOPC:29</a></i>;<br/>
<a NAME="E48:89_1"/>
<font color="Maroon">Dp</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 
<b>by </b><i><a class="ref" href="xboole_1.html#T36">XBOOLE_1:36</a></i>;<br/>
<a NAME="E49:89_1"/><b>then </b><i><font color="Green">E82</font></i>: 
<font color="Maroon">f</font> <a href="relset_1.html#K11">"</a> <font color="Maroon">E</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 
<b>by </b><i><a class="ref" href="borsuk_4.html#T18" target="_self">Th18</a>, <a class="ref" href="borsuk_4.html#T17" target="_self">Th17</a>, <a class="ref" href="xboole_1.html#T1">XBOOLE_1:1</a></i>;<br/>
<a NAME="E50:89_1"/>
<font color="Maroon">f</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><font color="Maroon">f</font> <a href="relset_1.html#K11">"</a> <font color="Maroon">E</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">E</font>
 
<b>by </b><i>, <a class="ref" href="funct_1.html#T147">FUNCT_1:147</a></i>;<br/>
<b>then consider </b><font color="Maroon">s1</font> being   <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">s2</font> being   <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><b> such that </b><br/><a NAME="E52:89_1"/><i><font color="Green">E190</font></i>: 
<font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">s1</font>,<font color="Maroon">s2</font>
 <b>by </b><i>, <a class="txt" href="borsuk_4.html#E31:89_1"><i><font color="Green">E71</font></i></a>, <a class="ref" href="borsuk_4.html#T18" target="_self">Th18</a>, <a class="ref" href="borsuk_4.html#T17" target="_self">Th17</a>, <a class="ref" href="borsuk_4.html#T15" target="_self">Th15</a></i>;<br/>
<b>take </b>
<font color="Maroon">s1</font>
;<br/>

<b>take </b>
<font color="Maroon">s2</font>
;<br/>

<b>take </b>
<font color="Maroon">B</font>
;<br/>

<b>thus </b><a NAME="E53:89_1"/>
<font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">s1</font>,<font color="Maroon">s2</font>
 <b>by </b><i><a class="ref" href="borsuk_4.html#T20" target="_self">Th20</a></i>;<br/>

<a NAME="E54:89_1"/>
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font>
 
<b>by </b><i>, <a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<b>hence </b><a NAME="E55:89_1"/>
( <font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font> &amp; <font color="Maroon">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> )
 <b>by </b><i><a class="ref" href="borsuk_4.html#T19" target="_self">Th19</a>, <a class="ref" href="funct_1.html#T163">FUNCT_1:163</a>, <a class="ref" href="borsuk_4.html#T12" target="_self">Th12</a></i>;<br/>


</div><b>end;</b></div>
<div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:89_2"/>
( <font color="Maroon">C</font> is <a href="realset1.html#V1">trivial</a> or  not <font color="Maroon">C</font> is <a href="realset1.html#V1">trivial</a> )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2_1"><b>suppose </b></a><a NAME="E1:89_2_1"/><i><font color="Green">E191</font></i>: 
<font color="Maroon">C</font> is <a href="realset1.html#V1">trivial</a>
 ;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2_1_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:89_2_1_1"/>
( <font color="Maroon">C</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  or <font color="Maroon">C</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2_1_1_1"><b>suppose </b></a><a NAME="E1:89_2_1_1_1"/><i><font color="Green">E192</font></i>: 
<font color="Maroon">C</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 ;<br/><div class="add"><b>consider </b><font color="Maroon">p</font> being   <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">q</font> being   <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><b> such that </b><br/><a NAME="E3:89_2_1_1_1"/><i><font color="Green">E193</font></i>: 
( <font color="Maroon">p</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">q</font> &amp; <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font> &amp; <font color="Maroon">q</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font> )
 <b>by </b><i><a class="ref" href="topreal2.html#T4">TOPREAL2:4</a></i>;<br/><b>reconsider </b><font color="Maroon">CC</font> = <span class="p1"><a href="domain_1.html#K7">{</a><span class="default"><font color="Maroon">p</font>,<font color="Maroon">q</font></span><a href="domain_1.html#K7">}</a></span> as   <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/><a NAME="E5:89_2_1_1_1"/>
( <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">CC</font> &amp; <font color="Maroon">q</font> <a href="hidden.html#R2">in</a> <font color="Maroon">CC</font> )
 <b>by </b><i><a class="ref" href="tarski.html#D2">TARSKI:def 2</a></i>;<br/><a NAME="E6:89_2_1_1_1"/><b>then </b><i><font color="Green">E195</font></i>: 
not <font color="Maroon">CC</font> is <a href="realset1.html#V1">trivial</a>
 <b>by </b><i>, <a class="ref" href="realset1.html#T14">REALSET1:14</a></i>;<br/><b>reconsider </b><font color="Maroon">pp</font> = <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">p</font></span><a href="domain_1.html#K6">}</a></span>, <font color="Maroon">qq</font> = <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">q</font></span><a href="domain_1.html#K6">}</a></span> as   <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/><a NAME="E8:89_2_1_1_1"/>
<font color="Maroon">CC</font> <a href="hidden.html#R1">=</a> <font color="Maroon">pp</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">qq</font>
 <b>by </b><i><a class="ref" href="enumset1.html#T41">ENUMSET1:41</a></i>;<br/><a NAME="E9:89_2_1_1_1"/><b>then </b><i><font color="Green">E196</font></i>: 
<font color="Maroon">CC</font> is <a href="compts_1.html#V6">compact</a>
 <b>by </b><i><a class="ref" href="compts_1.html#T19">COMPTS_1:19</a></i>;<br/><a NAME="E10:89_2_1_1_1"/><i><font color="Green">E197</font></i>: 
<font color="Maroon">CC</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 <b>by </b><i>, <a class="ref" href="zfmisc_1.html#T38">ZFMISC_1:38</a></i>;<br/><a NAME="E11:89_2_1_1_1"/>
<font color="Maroon">CC</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">D</font>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="89_2_1_1_1_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:89_2_1_1_1_1"/>
<font color="Maroon">CC</font> <a href="hidden.html#R1">=</a> <font color="Maroon">D</font>
 ;<br/>

<a NAME="E2:89_2_1_1_1_1"/><b>then </b><i><font color="Green">E200</font></i>: 
<font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">CC</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="xboole_1.html#T37">XBOOLE_1:37</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">E</font> = <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">CC</font> as   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">D</font></span>)</span> <b>by </b><i><a class="ref" href="xboole_1.html#T2">XBOOLE_1:2</a></i>;<br/>
<a NAME="E4:89_2_1_1_1_1"/>
not  <a href="pre_topc.html#K1">{}</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">D</font></span>)</span> is <a href="connsp_1.html#V2">connected</a>
 
<b>by </b><i>, <a class="ref" href="jordan6.html#T60">JORDAN6:60</a>, </i>;<br/>
<b>hence </b><a NAME="E5:89_2_1_1_1_1"/>
contradiction
 ;<br/>


</div><b>end;</b></div><b>then consider </b><font color="Maroon">p1</font> being   <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">p2</font> being   <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">B</font> being   <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><b> such that </b><br/><a NAME="E13:89_2_1_1_1"/><i><font color="Green">E201</font></i>: 
( <font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">p1</font>,<font color="Maroon">p2</font> &amp; <font color="Maroon">CC</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font> &amp; <font color="Maroon">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> )
 <b>by </b><i>, <a class="ref" href="borsuk_4.html#T7" target="_self">Th7</a>, , </i>;<br/><b>take </b>
<font color="Maroon">p1</font>
;<br/><b>take </b>
<font color="Maroon">p2</font>
;<br/><b>take </b>
<font color="Maroon">B</font>
;<br/><b>thus </b><a NAME="E14:89_2_1_1_1"/>
<font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">p1</font>,<font color="Maroon">p2</font>
 <b>by </b><i/>;<br/><b>thus </b><a NAME="E15:89_2_1_1_1"/>
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font>
 <b>by </b><i>, <a class="ref" href="xboole_1.html#T2">XBOOLE_1:2</a></i>;<br/><b>thus </b><a NAME="E16:89_2_1_1_1"/>
<font color="Maroon">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 <b>by </b><i/>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2_1_1_2"><b>suppose </b></a><a NAME="E1:89_2_1_1_2"/>
<font color="Maroon">C</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 ;<br/><div class="add"><b>then consider </b><font color="Maroon">x</font> being   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span><b> such that </b><br/><a NAME="E3:89_2_1_1_2"/><i><font color="Green">E203</font></i>: 
<font color="Maroon">C</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">x</font></span><a href="domain_1.html#K6">}</a></span>
 <b>by </b><i>, </i>;<br/><a NAME="E4:89_2_1_1_2"/><i><font color="Green">E204</font></i>: 
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font>
 <b>by </b><i>, <a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/><a NAME="E5:89_2_1_1_2"/><b>then </b><i><font color="Green">E205</font></i>: 
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font>
 <b>by </b><i/>;<br/><b>consider </b><font color="Maroon">y</font> being    <a href="subset_1.html#M2">Element</a> of <font color="Maroon">D</font><b> such that </b><br/><a NAME="E7:89_2_1_1_2"/><i><font color="Green">E206</font></i>: 
<font color="Maroon">x</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">y</font>
 <b>by </b><i/>;<br/><b>reconsider </b><font color="Maroon">y'</font> = <font color="Maroon">y</font> as   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> ;<br/><b>reconsider </b><font color="Maroon">Y</font> = <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">y'</font></span><a href="domain_1.html#K6">}</a></span> as  non <a href="xboole_0.html#V1">empty</a> <a href="compts_1.html#V6">compact</a> <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>reconsider </b><font color="Maroon">Cy</font> = <font color="Maroon">C</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">Y</font> as  non <a href="xboole_0.html#V1">empty</a> <a href="compts_1.html#V6">compact</a> <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> <b>by </b><i>, <a class="ref" href="compts_1.html#T19">COMPTS_1:19</a></i>;<br/><a NAME="E11:89_2_1_1_2"/><i><font color="Green">E207</font></i>: 
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Cy</font>
 <b>by </b><i><a class="ref" href="xboole_1.html#T7">XBOOLE_1:7</a></i>;<br/><a NAME="E12:89_2_1_1_2"/>
<font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font>
 <b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/><a NAME="E13:89_2_1_1_2"/><b>then </b>
<font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Cy</font>
 <b>by </b><i><a class="ref" href="xboole_0.html#D2">XBOOLE_0:def 2</a></i>;<br/><a NAME="E14:89_2_1_1_2"/><b>then </b><i><font color="Green">E208</font></i>: 
not <font color="Maroon">Cy</font> is <a href="realset1.html#V1">trivial</a>
 <b>by </b><i>, , <a class="ref" href="borsuk_4.html#T7" target="_self">Th7</a>, <a class="ref" href="realset1.html#T14">REALSET1:14</a></i>;<br/><a NAME="E15:89_2_1_1_2"/>
<span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">y</font></span><a href="domain_1.html#K6">}</a></span> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 ;<br/><a NAME="E16:89_2_1_1_2"/><b>then </b><i><font color="Green">E210</font></i>: 
<font color="Maroon">Cy</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 <b>by </b><i>, <a class="ref" href="xboole_1.html#T8">XBOOLE_1:8</a></i>;<br/><a NAME="E17:89_2_1_1_2"/>
<font color="Maroon">Cy</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">D</font>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="89_2_1_1_2_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:89_2_1_1_2_1"/>
<font color="Maroon">Cy</font> <a href="hidden.html#R1">=</a> <font color="Maroon">D</font>
 ;<br/>

<a NAME="E2:89_2_1_1_2_1"/><b>then </b><i><font color="Green">E211</font></i>: 
<font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">Cy</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="xboole_1.html#T37">XBOOLE_1:37</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">E</font> = <font color="Maroon">D</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">Cy</font> as   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">D</font></span>)</span> <b>by </b><i><a class="ref" href="xboole_1.html#T2">XBOOLE_1:2</a></i>;<br/>
<a NAME="E4:89_2_1_1_2_1"/>
<font color="Maroon">Cy</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K7">{</a><span class="default"><font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="domain_1.html#K7">}</a></span>
 
<b>by </b><i>, <a class="ref" href="enumset1.html#T41">ENUMSET1:41</a></i>;<br/>
<a NAME="E5:89_2_1_1_2_1"/><b>then </b>
not  <a href="pre_topc.html#K1">{}</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 2</span>)</span> <a href="pre_topc.html#K3">|</a> <font color="Maroon">D</font></span>)</span> is <a href="connsp_1.html#V2">connected</a>
 
<b>by </b><i><a class="ref" href="jordan6.html#T60">JORDAN6:60</a>, , , <a class="ref" href="borsuk_4.html#T7" target="_self">Th7</a></i>;<br/>
<b>hence </b><a NAME="E6:89_2_1_1_2_1"/>
contradiction
 ;<br/>


</div><b>end;</b></div><b>then consider </b><font color="Maroon">p1</font> being   <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">p2</font> being   <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">B</font> being   <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><b> such that </b><br/><a NAME="E19:89_2_1_1_2"/><i><font color="Green">E212</font></i>: 
( <font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">p1</font>,<font color="Maroon">p2</font> &amp; <font color="Maroon">Cy</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font> &amp; <font color="Maroon">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> )
 <b>by </b><i>, , </i>;<br/><b>take </b>
<font color="Maroon">p1</font>
;<br/><b>take </b>
<font color="Maroon">p2</font>
;<br/><b>take </b>
<font color="Maroon">B</font>
;<br/><b>thus </b><a NAME="E20:89_2_1_1_2"/>
<font color="Maroon">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Maroon">p1</font>,<font color="Maroon">p2</font>
 <b>by </b><i/>;<br/><b>thus </b><a NAME="E21:89_2_1_1_2"/>
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font>
 <b>by </b><i>, <a class="ref" href="xboole_1.html#T1">XBOOLE_1:1</a>, </i>;<br/><b>thus </b><a NAME="E22:89_2_1_1_2"/>
<font color="Maroon">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font>
 <b>by </b><i/>;<br/></div><b>end;</b></div></div><b>end;</b></div></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="89_2_2"><b>suppose </b></a><a NAME="E1:89_2_2"/>
not <font color="Maroon">C</font> is <a href="realset1.html#V1">trivial</a>
 ;<br/><div class="add"><b>hence </b><a NAME="E2:89_2_2"/>
 ex <font color="Olive">p1</font>, <font color="Olive">p2</font> being  <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> ex <font color="Olive">B</font> being  <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> st <br/>( <font color="Olive">B</font> <a href="topreal1.html#R1">is_an_arc_of</a> <font color="Olive">p1</font>,<font color="Olive">p2</font> &amp; <font color="Maroon">C</font> <a href="tarski.html#R1">c=</a> <font color="Olive">B</font> &amp; <font color="Olive">B</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">D</font> )
 <b>by </b><i>, , , </i>;<br/></div><b>end;</b></div></div><b>end;</b></div>

</div>
