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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>let </b><font color="Maroon">F</font> be    <a href="cat_1.html#M2">Functor</a> of <font color="Maroon">A</font>,<font color="Maroon">B</font>;<br/><b>let </b><font color="Maroon">G</font> be    <a href="cat_1.html#M2">Functor</a> of <font color="Maroon">B</font>,<font color="Maroon">A</font>;<br/><b>let </b><font color="Maroon">I</font> be    <a href="cat_1.html#M2">Functor</a> of <font color="Maroon">A</font>,<font color="Maroon">A</font>;<br/>









<a NAME="E1:54"/>
( <font color="Maroon">F</font> <a href="cat_1.html#K14">*</a> <span class="p1">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">A</font></span>)</span> <a href="funct_2.html#R2">=</a> <font color="Maroon">F</font> &amp; <span class="p1">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">A</font></span>)</span> <a href="cat_1.html#K14">*</a> <font color="Maroon">G</font> <a href="funct_2.html#R2">=</a> <font color="Maroon">G</font> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E2:54"/>
( <font color="Maroon">I</font> <a href="nattra_1.html#NR4" target="_self">~=</a>  <a href="cat_1.html#K15">id</a> <font color="Maroon">A</font> implies ( <font color="Maroon">F</font> <a href="cat_1.html#K14">*</a> <font color="Maroon">I</font> <a href="nattra_1.html#NR4" target="_self">~=</a> <font color="Maroon">F</font> &amp; <font color="Maroon">I</font> <a href="cat_1.html#K14">*</a> <font color="Maroon">G</font> <a href="nattra_1.html#NR4" target="_self">~=</a> <font color="Maroon">G</font> ) )
 <b>by </b><i/>;<br/>


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