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<b>let </b><font color="Maroon">A</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> , <font color="Maroon">B</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">F</font> be  <a href="functor0.html#V6">reflexive</a> <a href="functor0.html#V8">feasible</a>  <a href="functor0.html#L2">FunctorStr</a> of <font color="Maroon">A</font>,<font color="Maroon">B</font>;<br/>



<b>assume </b><a NAME="E1:1"/><i><font color="Green">E25</font></i>: 
( <font color="Maroon">F</font> is <a href="functor0.html#V7">coreflexive</a> &amp; <font color="Maroon">F</font> is <a href="functor0.html#V21">bijective</a> )
 ;<br/>

<b>let </b><font color="Maroon">a</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">A</font>;<br/><b>let </b><font color="Maroon">b</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">B</font>;<br/>



<a NAME="E2:1"/>
<span class="p1">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K15">"</a> </span>)</span> <a href="functor0.html#K13">*</a> <font color="Maroon">F</font> <a href="hidden.html#R1">=</a>  <a href="functor0.html#K12">id</a> <font color="Maroon">A</font>
 
<b>by </b><i>, <a class="ref" href="functor1.html#T22">FUNCTOR1:22</a></i>;<br/>
<a NAME="E3:1"/><b>then </b>
<font color="Maroon">a</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K15">"</a> </span>)</span> <a href="functor0.html#K13">*</a> <font color="Maroon">F</font></span>)</span> <a href="functor0.html#K3">.</a> <font color="Maroon">a</font>
 
<b>by </b><i><a class="ref" href="functor0.html#T30">FUNCTOR0:30</a></i>;<br/>
<b>hence </b><a NAME="E4:1"/>
( <font color="Maroon">F</font> <a href="functor0.html#K3">.</a> <font color="Maroon">a</font> <a href="hidden.html#R1">=</a> <font color="Maroon">b</font> implies <span class="p1">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K15">"</a> </span>)</span> <a href="functor0.html#K3">.</a> <font color="Maroon">b</font> <a href="hidden.html#R1">=</a> <font color="Maroon">a</font> )
 <b>by </b><i><a class="ref" href="functor0.html#T34">FUNCTOR0:34</a></i>;<br/>

<b>reconsider </b><font color="Maroon">G</font> = <font color="Maroon">F</font> <a href="functor0.html#K15">"</a>  as  <a href="functor0.html#V6">reflexive</a> <a href="functor0.html#V8">feasible</a>  <a href="functor0.html#L2">FunctorStr</a> of <font color="Maroon">B</font>,<font color="Maroon">A</font> <b>by </b><i>, <a class="ref" href="functor0.html#T36">FUNCTOR0:36</a>, <a class="ref" href="functor0.html#T37">FUNCTOR0:37</a></i>;<br/>
<a NAME="E6:1"/>
<font color="Maroon">F</font> <a href="functor0.html#K13">*</a> <font color="Maroon">G</font> <a href="hidden.html#R1">=</a>  <a href="functor0.html#K12">id</a> <font color="Maroon">B</font>
 
<b>by </b><i>, <a class="ref" href="functor1.html#T21">FUNCTOR1:21</a></i>;<br/>
<a NAME="E7:1"/><b>then </b>
<font color="Maroon">b</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K13">*</a> <font color="Maroon">G</font></span>)</span> <a href="functor0.html#K3">.</a> <font color="Maroon">b</font>
 
<b>by </b><i><a class="ref" href="functor0.html#T30">FUNCTOR0:30</a></i>;<br/>
<b>hence </b><a NAME="E8:1"/>
( <span class="p1">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K15">"</a> </span>)</span> <a href="functor0.html#K3">.</a> <font color="Maroon">b</font> <a href="hidden.html#R1">=</a> <font color="Maroon">a</font> implies <font color="Maroon">F</font> <a href="functor0.html#K3">.</a> <font color="Maroon">a</font> <a href="hidden.html#R1">=</a> <font color="Maroon">b</font> )
 <b>by </b><i><a class="ref" href="functor0.html#T34">FUNCTOR0:34</a></i>;<br/>


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