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<b>let </b><font color="Maroon" title="c1">C</font> be   <a href="cat_1.html#NM4" title="CAT_1:NM.4">Category</a>;<br/><b>let </b><font color="Maroon" title="c2">x</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ;<br/>



<a NAME="E1:41"/>
<font color="Maroon" title="c1">C</font> <a href="oppcat_1.html#K2" title="OPPCAT_1:func.2">opp</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="cat_1.html#G1" title="CAT_1:aggr.1">CatStr</a>(# the <a href="cat_1.html#U1" title="CAT_1:sel.1">Objects</a> of <font color="Maroon" title="c1">C</font>,the <a href="cat_1.html#U2" title="CAT_1:sel.2">Morphisms</a> of <font color="Maroon" title="c1">C</font>,the <a href="cat_1.html#U4" title="CAT_1:sel.4">Cod</a> of <font color="Maroon" title="c1">C</font>,the <a href="cat_1.html#U3" title="CAT_1:sel.3">Dom</a> of <font color="Maroon" title="c1">C</font>,<span class="p1">(<span class="default"><a href="oppcat_1.html#K1" title="OPPCAT_1:func.1">~</a> the <a href="cat_1.html#U5" title="CAT_1:sel.5">Comp</a> of <font color="Maroon" title="c1">C</font></span>)</span>,the <a href="cat_1.html#U6" title="CAT_1:sel.6">Id</a> of <font color="Maroon" title="c1">C</font> #)
 
<b>by </b><i><a class="ref" href="oppcat_1.html#D1" title="OPPCAT_1:def.1">OPPCAT_1:def 1</a></i>;<br/>
<b>hence </b><a NAME="E2:41"/>
( <font color="Maroon" title="c2">x</font> is   <a href="index_1.html#NM10" title="INDEX_1:NM.10">coIndexing</a> of <font color="Maroon" title="c1">C</font> iff <font color="Maroon" title="c2">x</font> is   <a href="index_1.html#NM9" title="INDEX_1:NM.9">Indexing</a> of <span class="p1">(<span class="default"><font color="Maroon" title="c1">C</font> <a href="oppcat_1.html#K2" title="OPPCAT_1:func.2">opp</a> </span>)</span> )
 ;<br/>


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