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<span class="kw">let </span><font color="Maroon" title="c1">A</font>, <font color="Maroon" title="c2">B</font>, <font color="Maroon" title="c3">C</font>, <font color="Maroon" title="c4">D</font> be   <a href="altcat_1.html#NM4" title="ALTCAT_1:NM.4">category</a>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> ( <font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c2">B</font> <a href="yellow18.html#R2" title="YELLOW18:pred.2">are_opposite</a>  &amp; <font color="Maroon" title="c3">C</font>,<font color="Maroon" title="c4">D</font> <a href="yellow18.html#R2" title="YELLOW18:pred.2">are_opposite</a>  &amp; <font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c3">C</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  implies <font color="Maroon" title="c2">B</font>,<font color="Maroon" title="c4">D</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  )</span><br/>

<span class="kw">assume </span><span class="kw">that </span><br/><a NAME="E1:42"/><span class="lab"><font color="Green" title="E20">A1</font></span>: 
<font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c2">B</font> <a href="yellow18.html#R2" title="YELLOW18:pred.2">are_opposite</a> 
 <span class="kw">and </span><br/><a NAME="E2:42"/><span class="lab"><font color="Green" title="E21">A2</font></span>: 
<font color="Maroon" title="c3">C</font>,<font color="Maroon" title="c4">D</font> <a href="yellow18.html#R2" title="YELLOW18:pred.2">are_opposite</a> 
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> (  not <font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c3">C</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  or <font color="Maroon" title="c2">B</font>,<font color="Maroon" title="c4">D</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  )</span><br/>

<a NAME="E3:42"/>
( <font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c3">C</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  implies <font color="Maroon" title="c2">B</font>,<font color="Maroon" title="c3">C</font> <a href="functor0.html#R2" title="FUNCTOR0:pred.2">are_anti-isomorphic</a>  )
 
<span class="kw">by</span> <span class="lab"><a class="txt" href="#E1:42"><span class="lab"><font color="Green" title="E20">A1</font></span></a>, <a class="ref" href="yellow18.html#T18" target="_self" title="YELLOW18:th.18">Th18</a></span>;<br/>
<span class="kw">hence </span><a NAME="E4:42"/>
(  not <font color="Maroon" title="c1">A</font>,<font color="Maroon" title="c3">C</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  or <font color="Maroon" title="c2">B</font>,<font color="Maroon" title="c4">D</font> <a href="functor0.html#R1" title="FUNCTOR0:pred.1">are_isomorphic</a>  )
 <span class="kw">by</span> <span class="lab"><a class="txt" href="#E2:42"><span class="lab"><font color="Green" title="E21">A2</font></span></a>, <a class="ref" href="yellow18.html#T18" target="_self" title="YELLOW18:th.18">Th18</a></span>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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