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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be   <a href="mod_1.html#NM1">AddGroup</a>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font> be    <a href="grcat_1.html#M1" target="_self">Morphism</a> of <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>;<br/>





<i><font color="Green">E22</font></i>: the <a href="grcat_1.html#U1" target="_self">Dom</a> of <font color="Maroon">c<sub>3</sub></font> = 
 <a href="grcat_1.html#K9" target="_self">dom</a> <font color="Maroon">c<sub>3</sub></font>

<br/>.= 
<font color="Maroon">c<sub>1</sub></font>
<b>by </b><i><a class="ref" href="grcat_1.html#D19" target="_self">Def19</a></i>
;<br/>
<i><font color="Green">E23</font></i>: the <a href="grcat_1.html#U2" target="_self">Cod</a> of <font color="Maroon">c<sub>3</sub></font> = 
 <a href="grcat_1.html#K10" target="_self">cod</a> <font color="Maroon">c<sub>3</sub></font>

<br/>.= 
<font color="Maroon">c<sub>2</sub></font>
<b>by </b><i><a class="ref" href="grcat_1.html#D19" target="_self">Def19</a></i>
;<br/>
<b>then reconsider </b><font color="Maroon">c<sub>4</sub></font> = the <a href="grcat_1.html#U3" target="_self">Fun</a> of <font color="Maroon">c<sub>3</sub></font> as   <a href="struct_0.html#NM7">Function</a> of <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font> <b>by </b><i><a class="txt" href="grcat_1.html#E1:41"><i><font color="Green">E22</font></i></a></i>;<br/>
<b>take </b>
<font color="Maroon">c<sub>4</sub></font>
;<br/>

<b>thus </b><a NAME="E4:41"/>
(  <a href="grcat_1.html#G1" target="_self">GroupMorphismStr</a>(# the <a href="grcat_1.html#U1" target="_self">Dom</a> of <font color="Maroon">c<sub>3</sub></font>,the <a href="grcat_1.html#U2" target="_self">Cod</a> of <font color="Maroon">c<sub>3</sub></font>,the <a href="grcat_1.html#U3" target="_self">Fun</a> of <font color="Maroon">c<sub>3</sub></font> #) <a href="hidden.html#R1">=</a>  <a href="grcat_1.html#G1" target="_self">GroupMorphismStr</a>(# <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>4</sub></font> #) &amp; <font color="Maroon">c<sub>4</sub></font> is <a href="grcat_1.html#V1" target="_self">additive</a> )
 <b>by </b><i><a class="txt" href="grcat_1.html#E1:41"><i><font color="Green">E22</font></i></a>, <a class="txt" href="grcat_1.html#E2:41"><i><font color="Green">E23</font></i></a>, <a class="ref" href="grcat_1.html#T18" target="_self">Th18</a></i>;<br/>


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