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<b>let </b><font color="Maroon" title="c1">G</font> be   <a href="group_1.html#NM1" title="GROUP_1:NM.1">Group</a>;<br/><b>let </b><font color="Maroon" title="c2">N</font> be  <a href="group_1.html#V1" title="GROUP_1:attr.1">strict</a> <a href="group_3.html#V1" title="GROUP_3:attr.1">normal</a>  <a href="group_2.html#M1" title="GROUP_2:mode.1">Subgroup</a> of <font color="Maroon" title="c1">G</font>;<br/><b>let </b><font color="Maroon" title="c3">a</font> be   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">G</font>; <i><font color="Red">:: according to </font></i><a class="ref" href="group_2.html#D6" title="GROUP_2:def.6">GROUP_2:def 6</a><br/>





<b>thus </b><a NAME="E1:59"/>
( <font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a>  <a href="group_6.html#K11" title="GROUP_6:func.11">Ker</a> <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span> implies <font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a> <font color="Maroon" title="c2">N</font> )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="59_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:59_1"/>
<font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a>  <a href="group_6.html#K11" title="GROUP_6:func.11">Ker</a> <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span>
 ;<br/>

<a NAME="E2:59_1"/><b>then </b>
( <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c3">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="group_1.html#K2" title="GROUP_1:func.2">1_</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">G</font> <a href="group_6.html#K6" title="GROUP_6:func.6">./.</a> <font color="Maroon" title="c2">N</font></span>)</span> &amp; <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c3">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">a</font> <a href="group_2.html#K12" title="GROUP_2:func.12">*</a> <font color="Maroon" title="c2">N</font> &amp;  <a href="group_1.html#K2" title="GROUP_1:func.2">1_</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">G</font> <a href="group_6.html#K6" title="GROUP_6:func.6">./.</a> <font color="Maroon" title="c2">N</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="group_2.html#K7" title="GROUP_2:func.7">carr</a> <font color="Maroon" title="c2">N</font> )
 
<b>by </b><i><a class="ref" href="group_6.html#D9" target="_self" title="GROUP_6:def.9">Def9</a>, <a class="ref" href="group_6.html#T29" target="_self" title="GROUP_6:th.29">Th29</a>, <a class="ref" href="group_6.html#T50" target="_self" title="GROUP_6:th.50">Th50</a></i>;<br/>
<b>hence </b><a NAME="E3:59_1"/>
<font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a> <font color="Maroon" title="c2">N</font>
 <b>by </b><i><a class="ref" href="group_2.html#T136" title="GROUP_2:th.136">GROUP_2:136</a></i>;<br/>


</div><b>end;</b></div>

<b>assume </b><a NAME="E2:59"/>
<font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a> <font color="Maroon" title="c2">N</font>
 ;<br/>

<a NAME="E3:59"/><b>then </b>
( <font color="Maroon" title="c3">a</font> <a href="group_2.html#K12" title="GROUP_2:func.12">*</a> <font color="Maroon" title="c2">N</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="group_2.html#K7" title="GROUP_2:func.7">carr</a> <font color="Maroon" title="c2">N</font> &amp; <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c3">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">a</font> <a href="group_2.html#K12" title="GROUP_2:func.12">*</a> <font color="Maroon" title="c2">N</font> &amp;  <a href="group_1.html#K2" title="GROUP_1:func.2">1_</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">G</font> <a href="group_6.html#K6" title="GROUP_6:func.6">./.</a> <font color="Maroon" title="c2">N</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="group_2.html#K7" title="GROUP_2:func.7">carr</a> <font color="Maroon" title="c2">N</font> )
 
<b>by </b><i><a class="ref" href="group_6.html#D9" target="_self" title="GROUP_6:def.9">Def9</a>, <a class="ref" href="group_6.html#T29" target="_self" title="GROUP_6:th.29">Th29</a>, <a class="ref" href="group_2.html#T136" title="GROUP_2:th.136">GROUP_2:136</a></i>;<br/>
<b>hence </b><a NAME="E4:59"/>
<font color="Maroon" title="c3">a</font> <a href="struct_0.html#R1" title="STRUCT_0:pred.1">in</a>  <a href="group_6.html#K11" title="GROUP_6:func.11">Ker</a> <span class="p1">(<span class="default"><a href="group_6.html#K10" title="GROUP_6:func.10">nat_hom</a> <font color="Maroon" title="c2">N</font></span>)</span>
 <b>by </b><i><a class="ref" href="group_6.html#T50" target="_self" title="GROUP_6:th.50">Th50</a></i>;<br/>


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