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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be  non <a href="struct_0.html#V3">empty</a> <a href="altcat_1.html#V2">transitive</a> <a href="altcat_1.html#V12">with_units</a>  <a href="altcat_1.html#L2">AltCatStr</a> ;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be  <a href="functor0.html#V15">covariant</a>  <a href="functor0.html#M2">Functor</a> of <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>;<br/>



<b>assume </b><a NAME="E1:22"/>
<font color="Maroon">c<sub>3</sub></font> <a href="functor2.html#R2" target="_self">is_naturally_transformable_to</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<a NAME="E2:22"/><b>then </b><i><font color="Green">E19</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="functor2.html#R1" target="_self">is_transformable_to</a> <font color="Maroon">c<sub>4</sub></font>
 
<b>by </b><i><a class="ref" href="functor2.html#D6" target="_self">Def6</a></i>;<br/>
<b>let </b><font color="Maroon">c<sub>5</sub></font> be    <a href="functor2.html#M2" target="_self">natural_transformation</a> of <font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font>;<br/>

<b>thus </b><a NAME="E3:22"/>
<span class="p1">(<span class="default"><a href="functor2.html#K4" target="_self">idt</a> <font color="Maroon">c<sub>4</sub></font></span>)</span> <a href="functor2.html#K3" target="_self">`*`</a> <font color="Maroon">c<sub>5</sub></font> <a href="pboole.html#R6">=</a> <font color="Maroon">c<sub>5</sub></font>
 <b>by </b><i><a class="txt" href="functor2.html#E2:22"><i><font color="Green">E19</font></i></a>, <a class="ref" href="functor2.html#T7" target="_self">Th7</a></i>;<br/>

<b>thus </b><a NAME="E4:22"/>
<font color="Maroon">c<sub>5</sub></font> <a href="functor2.html#K3" target="_self">`*`</a> <span class="p1">(<span class="default"><a href="functor2.html#K4" target="_self">idt</a> <font color="Maroon">c<sub>3</sub></font></span>)</span> <a href="pboole.html#R6">=</a> <font color="Maroon">c<sub>5</sub></font>
 <b>by </b><i><a class="txt" href="functor2.html#E2:22"><i><font color="Green">E19</font></i></a>, <a class="ref" href="functor2.html#T7" target="_self">Th7</a></i>;<br/>


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