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<b>let </b><font color="Maroon">A</font> be   <a href="cat_1.html#NM4">Category</a>;<br/><b>let </b><font color="Maroon">B</font> be   <a href="cat_1.html#NM4">Category</a>;<br/>



<b>assume </b><b>that </b><br/><a NAME="E1:70"/><i><font color="Green">E7</font></i>: 
<font color="Maroon">A</font> is <a href="nattra_1.html#V2" target="_self">discrete</a>
 <b>and </b><br/><a NAME="E2:70"/><i><font color="Green">E8</font></i>: 
<font color="Maroon">B</font> is <a href="nattra_1.html#V2" target="_self">discrete</a>
 ;<br/>

<b>let </b><font color="Maroon">f</font> be   <a href="cat_1.html#NM2">Morphism</a> of <span class="p1"><a href="cat_2.html#K11">[:</a><span class="default"><font color="Maroon">A</font>,<font color="Maroon">B</font></span><a href="cat_2.html#K11">:]</a></span>; <i><font color="Red">:: according to </font></i><a class="ref" href="nattra_1.html#D19" target="_self">NATTRA_1:def 19</a><br/>

<b>consider </b><font color="Maroon">f1</font> being   <a href="cat_1.html#NM2">Morphism</a> of <font color="Maroon">A</font>, <font color="Maroon">f2</font> being   <a href="cat_1.html#NM2">Morphism</a> of <font color="Maroon">B</font><b> such that </b><br/><a NAME="E4:70"/><i><font color="Green">E25</font></i>: 
<font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_2.html#K13">[</a><span class="default"><font color="Maroon">f1</font>,<font color="Maroon">f2</font></span><a href="cat_2.html#K13">]</a></span>
 <b>by </b><i><a class="ref" href="domain_1.html#T9">DOMAIN_1:9</a></i>;<br/>
<b>consider </b><font color="Maroon">a</font> being   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">A</font><b> such that </b><br/><a NAME="E6:70"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">f1</font> <a href="hidden.html#R1">=</a>  <a href="cat_1.html#K10">id</a> <font color="Maroon">a</font>
 <b>by </b><i>, </i>;<br/>
<b>consider </b><font color="Maroon">b</font> being   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">B</font><b> such that </b><br/><a NAME="E8:70"/><i><font color="Green">E27</font></i>: 
<font color="Maroon">f2</font> <a href="hidden.html#R1">=</a>  <a href="cat_1.html#K10">id</a> <font color="Maroon">b</font>
 <b>by </b><i>, </i>;<br/>
<b>take </b>
<span class="p1"><a href="cat_2.html#K12">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="cat_2.html#K12">]</a></span>
;<br/>

<b>thus </b><a NAME="E9:70"/>
<font color="Maroon">f</font> <a href="hidden.html#R1">=</a>  <a href="cat_1.html#K10">id</a> <span class="p1"><a href="cat_2.html#K12">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="cat_2.html#K12">]</a></span>
 <b>by </b><i>, , , <a class="ref" href="cat_2.html#T41">CAT_2:41</a></i>;<br/>


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