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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="topgrp_1.html#NM2">TopGroup</a>;<br/>

<b>assume </b><a NAME="E1:74"/><i><font color="Green">E38</font></i>: 
for <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><br/>for <font color="Olive">b<sub>2</sub></font> being   <a href="connsp_2.html#M1">a_neighborhood</a> of <font color="Olive">b<sub>1</sub></font> <a href="group_1.html#K3">"</a> ex <font color="Olive">b<sub>3</sub></font> being   <a href="connsp_2.html#M1">a_neighborhood</a> of <font color="Olive">b<sub>1</sub></font> st <font color="Olive">b<sub>3</sub></font> <a href="group_2.html#K1">"</a>  <a href="tarski.html#R1">c=</a> <font color="Olive">b<sub>2</sub></font>
 ;<br/>

<b>set </b><font color="Maroon">c<sub>2</sub></font> =  <a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font>;<br/>
<a NAME="E2:74"/>
for <font color="Olive">b<sub>1</sub></font> being  <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">c<sub>1</sub></font><br/>for <font color="Olive">b<sub>2</sub></font> being   <a href="connsp_2.html#M1">a_neighborhood</a> of <span class="p1">(<span class="default"><a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Olive">b<sub>1</sub></font>ex <font color="Olive">b<sub>3</sub></font> being   <a href="connsp_2.html#M1">a_neighborhood</a> of <font color="Olive">b<sub>1</sub></font> st <span class="p1">(<span class="default"><a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="relset_1.html#K10">.:</a> <font color="Olive">b<sub>3</sub></font> <a href="tarski.html#R1">c=</a> <font color="Olive">b<sub>2</sub></font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="74_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">c<sub>3</sub></font> be   <a href="pre_topc.html#NM2">Point</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="connsp_2.html#M1">a_neighborhood</a> of <span class="p1">(<span class="default"><a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">c<sub>3</sub></font>;<br/>



<a NAME="E1:74_1"/>
<span class="p1">(<span class="default"><a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>3</sub></font> <a href="group_1.html#K3">"</a> 
 
<b>by </b><i><a class="ref" href="group_1.html#D7">GROUP_1:def 7</a></i>;<br/>
<b>then consider </b><font color="Maroon">c<sub>5</sub></font> being    <a href="connsp_2.html#M1">a_neighborhood</a> of <font color="Maroon">c<sub>3</sub></font><b> such that </b><br/><a NAME="E3:74_1"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">c<sub>5</sub></font> <a href="group_2.html#K1">"</a>  <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="topgrp_1.html#E1:74"><i><font color="Green">E38</font></i></a></i>;<br/>
<b>take </b>
<font color="Maroon">c<sub>5</sub></font>
;<br/>

<b>thus </b><a NAME="E4:74_1"/>
<span class="p1">(<span class="default"><a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="relset_1.html#K10">.:</a> <font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="topgrp_1.html#E3:74_1"><i><font color="Green">E39</font></i></a>, <a class="ref" href="topgrp_1.html#T10" target="_self">Th10</a></i>;<br/>


</div><b>end;</b></div>
<b>hence </b><a NAME="E3:74"/>
 <a href="topgrp_1.html#K5" target="_self">inverse_op</a> <font color="Maroon">c<sub>1</sub></font> is <a href="pre_topc.html#V5">continuous</a>
 <b>by </b><i><a class="ref" href="borsuk_1.html#D3">BORSUK_1:def 3</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="topgrp_1.html#D6" target="_self">TOPGRP_1:def 6</a><br/>


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