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<b>let </b><font color="Maroon">C</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">G1</font> be    <a href="cat_1.html#M2">Functor</a> of <font color="Maroon">B</font>,<font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">G2</font> be    <a href="cat_1.html#M2">Functor</a> of <font color="Maroon">B</font>,<font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">t</font> be    <a href="nattra_1.html#M2">natural_transformation</a> of <font color="Maroon">G1</font>,<font color="Maroon">G2</font>;<br/>









<b>assume </b><a NAME="E1:48"/><i><font color="Green">E18</font></i>: 
<font color="Maroon">G1</font> <a href="nattra_1.html#R2">is_naturally_transformable_to</a> <font color="Maroon">G2</font>
 ;<br/>

<a NAME="E2:48"/><b>then </b><i><font color="Green">E19</font></i>: 
<font color="Maroon">G1</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">B</font></span>)</span> <a href="nattra_1.html#R2">is_naturally_transformable_to</a> <font color="Maroon">G2</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">B</font></span>)</span>
 
<b>by </b><i/>;<br/>
<b>thus </b><font color="Maroon">t</font> <a href="isocat_1.html#K6" target="_self">(#)</a> <span class="p1">(<span class="default"><a href="nattra_1.html#K7">id</a> <span class="p2">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">B</font></span>)</span></span>)</span> = 
<span class="p1">(<span class="default"><font color="Maroon">t</font> <a href="isocat_1.html#K5" target="_self">*</a> <span class="p2">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">B</font></span>)</span></span>)</span> <a href="nattra_1.html#K8">`*`</a> <span class="p1">(<span class="default"><a href="nattra_1.html#K7">id</a> <span class="p2">(<span class="default"><font color="Maroon">G1</font> <a href="cat_1.html#K14">*</a> <span class="p3">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">B</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i/>
<br/>.= 
<font color="Maroon">t</font> <a href="isocat_1.html#K5" target="_self">*</a> <span class="p1">(<span class="default"><a href="cat_1.html#K15">id</a> <font color="Maroon">B</font></span>)</span>
<b>by </b><i>, <a class="ref" href="nattra_1.html#T26">NATTRA_1:26</a></i>
<br/>.= 
<font color="Maroon">t</font>
<b>by </b><i>, <a class="ref" href="isocat_1.html#T4" target="_self">Th4</a></i>
;<br/>


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