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<b>let </b><font color="Maroon">c<sub>4</sub></font>, <font color="Maroon">c<sub>5</sub></font> be  non <a href="struct_0.html#V3">empty</a> <a href="pre_topc.html#NM1">TopSpace</a>;<br/><b>let </b><font color="Maroon">c<sub>6</sub></font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">c<sub>4</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>7</sub></font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">c<sub>5</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>8</sub></font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="topalg_1.html#NK4" target="_self">pi_1</a> <span class="p2"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>5</sub></font></span><a href="borsuk_1.html#K5">:]</a></span>,<span class="p2"><a href="borsuk_1.html#K7">[</a><span class="default"><font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span><a href="borsuk_1.html#K7">]</a></span></span>)</span>;<br/><b>let </b><font color="Maroon">c<sub>9</sub></font> be   <a href="topalg_1.html#NM1">Loop</a> of <span class="p1"><a href="borsuk_1.html#K7">[</a><span class="default"><font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span><a href="borsuk_1.html#K7">]</a></span>;<br/>











<b>consider </b><font color="Maroon">c<sub>10</sub></font> being   <a href="topalg_1.html#NM1">Loop</a> of <span class="p1"><a href="borsuk_1.html#K7">[</a><span class="default"><font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span><a href="borsuk_1.html#K7">]</a></span><b> such that </b><br/><a NAME="E2:40"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#R1">=</a>  <a href="eqrel_1.html#K7">Class</a> <span class="p1">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <span class="p2"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>5</sub></font></span><a href="borsuk_1.html#K5">:]</a></span>,<span class="p2"><a href="borsuk_1.html#K7">[</a><span class="default"><font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span><a href="borsuk_1.html#K7">]</a></span></span>)</span>,<font color="Maroon">c<sub>10</sub></font>
 <b>and </b><br/><a NAME="E3:40"/><i><font color="Green">E30</font></i>: 
<span class="p1">(<span class="default"><a href="topalg_4.html#K12" target="_self">FGPrIso</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><span class="p2">(<span class="default"><a href="eqrel_1.html#K7">Class</a> <span class="p3">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>6</sub></font></span>)</span>,<span class="p3">(<span class="default"><a href="topalg_4.html#K10" target="_self">pr1</a> <font color="Maroon">c<sub>10</sub></font></span>)</span></span>)</span>,<span class="p2">(<span class="default"><a href="eqrel_1.html#K7">Class</a> <span class="p3">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span>,<span class="p3">(<span class="default"><a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>10</sub></font></span>)</span></span>)</span></span><a href="finseq_1.html#K10">*&gt;</a></span>
 <b>by </b><i><a class="ref" href="topalg_4.html#D2" target="_self">Def2</a></i>;<br/>
<b>assume </b><a NAME="E4:40"/>
<font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#R1">=</a>  <a href="eqrel_1.html#K7">Class</a> <span class="p1">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <span class="p2"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>5</sub></font></span><a href="borsuk_1.html#K5">:]</a></span>,<span class="p2"><a href="borsuk_1.html#K7">[</a><span class="default"><font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span><a href="borsuk_1.html#K7">]</a></span></span>)</span>,<font color="Maroon">c<sub>9</sub></font>
 ;<br/>

<a NAME="E5:40"/><b>then </b><i><font color="Green">E31</font></i>: 
<font color="Maroon">c<sub>9</sub></font>,<font color="Maroon">c<sub>10</sub></font> <a href="borsuk_2.html#R3">are_homotopic</a> 
 
<b>by </b><i><a class="txt" href="topalg_4.html#E2:40"><i><font color="Green">E29</font></i></a>, <a class="ref" href="topalg_1.html#T47">TOPALG_1:47</a></i>;<br/>
<a NAME="E6:40"/><b>then </b><i><font color="Green">E32</font></i>: 
 <a href="topalg_4.html#K10" target="_self">pr1</a> <font color="Maroon">c<sub>9</sub></font>, <a href="topalg_4.html#K10" target="_self">pr1</a> <font color="Maroon">c<sub>10</sub></font> <a href="borsuk_2.html#R3">are_homotopic</a> 
 
<b>by </b><i><a class="ref" href="topalg_4.html#T19" target="_self">Th19</a></i>;<br/>
<a NAME="E7:40"/>
 <a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>9</sub></font>, <a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>10</sub></font> <a href="borsuk_2.html#R3">are_homotopic</a> 
 
<b>by </b><i><a class="txt" href="topalg_4.html#E5:40"><i><font color="Green">E31</font></i></a>, <a class="ref" href="topalg_4.html#T20" target="_self">Th20</a></i>;<br/>
<a NAME="E8:40"/><b>then </b>
 <a href="eqrel_1.html#K7">Class</a> <span class="p1">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span>,<span class="p1">(<span class="default"><a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>9</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="eqrel_1.html#K7">Class</a> <span class="p1">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span>,<span class="p1">(<span class="default"><a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>10</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="topalg_1.html#T47">TOPALG_1:47</a></i>;<br/>
<b>hence </b><a NAME="E9:40"/>
<span class="p1">(<span class="default"><a href="topalg_4.html#K12" target="_self">FGPrIso</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><span class="p2">(<span class="default"><a href="eqrel_1.html#K7">Class</a> <span class="p3">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>6</sub></font></span>)</span>,<span class="p3">(<span class="default"><a href="topalg_4.html#K10" target="_self">pr1</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span>,<span class="p2">(<span class="default"><a href="eqrel_1.html#K7">Class</a> <span class="p3">(<span class="default"><a href="topalg_1.html#K2">EqRel</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span>,<span class="p3">(<span class="default"><a href="topalg_4.html#K11" target="_self">pr2</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span><a href="finseq_1.html#K10">*&gt;</a></span>
 <b>by </b><i><a class="txt" href="topalg_4.html#E3:40"><i><font color="Green">E30</font></i></a>, <a class="txt" href="topalg_4.html#E6:40"><i><font color="Green">E32</font></i></a>, <a class="ref" href="topalg_1.html#T47">TOPALG_1:47</a></i>;<br/>


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