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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>, <font color="Maroon">c<sub>7</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>8</sub></font>, <font color="Maroon">c<sub>9</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>10</sub></font> be   <a href="group_6.html#NM2">Homomorphism</a> of <span class="p1">(<span class="default"><a href="topalg_1.html#NK4" target="_self">pi_1</a> <font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>6</sub></font></span>)</span>,<span class="p1">(<span class="default"><a href="topalg_1.html#NK4" target="_self">pi_1</a> <font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>7</sub></font></span>)</span>;<br/><b>let </b><font color="Maroon">c<sub>11</sub></font> be   <a href="group_6.html#NM2">Homomorphism</a> of <span class="p1">(<span class="default"><a href="topalg_1.html#NK4" target="_self">pi_1</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>8</sub></font></span>)</span>,<span class="p1">(<span class="default"><a href="topalg_1.html#NK4" target="_self">pi_1</a> <font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>9</sub></font></span>)</span>;<br/>















<b>assume </b><b>that </b><br/><a NAME="E1:46"/><i><font color="Green">E32</font></i>: 
<font color="Maroon">c<sub>10</sub></font> <a href="group_6.html#NR3" target="_self">is_isomorphism</a> 
 <b>and </b><br/><a NAME="E2:46"/><i><font color="Green">E33</font></i>: 
<font color="Maroon">c<sub>11</sub></font> <a href="group_6.html#NR3" target="_self">is_isomorphism</a> 
 ;<br/>

<a NAME="E3:46"/><i><font color="Green">E34</font></i>: 
 <a href="topalg_4.html#K13" target="_self">FGPrIso</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>8</sub></font> <a href="group_6.html#NR3" target="_self">is_isomorphism</a> 
 
<b>by </b><i><a class="ref" href="topalg_4.html#T29" target="_self">Th29</a></i>;<br/>
<a NAME="E4:46"/>
 <a href="topalg_4.html#K2" target="_self">Gr2Iso</a> <font color="Maroon">c<sub>10</sub></font>,<font color="Maroon">c<sub>11</sub></font> <a href="group_6.html#NR3" target="_self">is_isomorphism</a> 
 
<b>by </b><i><a class="txt" href="topalg_4.html#E1:46"><i><font color="Green">E32</font></i></a>, <a class="txt" href="topalg_4.html#E2:46"><i><font color="Green">E33</font></i></a>, <a class="ref" href="topalg_4.html#T5" target="_self">Th5</a></i>;<br/>
<b>hence </b><a NAME="E5:46"/>
<span class="p1">(<span class="default"><a href="topalg_4.html#K2" target="_self">Gr2Iso</a> <font color="Maroon">c<sub>10</sub></font>,<font color="Maroon">c<sub>11</sub></font></span>)</span> <a href="group_6.html#K8">*</a> <span class="p1">(<span class="default"><a href="topalg_4.html#K13" target="_self">FGPrIso</a> <font color="Maroon">c<sub>6</sub></font>,<font color="Maroon">c<sub>8</sub></font></span>)</span> <a href="group_6.html#NR3" target="_self">is_isomorphism</a> 
 <b>by </b><i><a class="txt" href="topalg_4.html#E3:46"><i><font color="Green">E34</font></i></a>, <a class="ref" href="group_6.html#T74">GROUP_6:74</a></i>;<br/>


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