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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">D</font> be   <a href="cat_1.html#NM4">Category</a>;<br/><b>let </b><font color="Maroon">c</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">d</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">D</font>;<br/>







<a NAME="E1:60"/><i><font color="Green">E18</font></i>: 
 <a href="cat_1.html#K10">id</a> <span class="p1"><a href="cat_2.html#K12" target="_self">[</a><span class="default"><font color="Maroon">c</font>,<font color="Maroon">d</font></span><a href="cat_2.html#K12" target="_self">]</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_2.html#K13" target="_self">[</a><span class="default"><span class="p2">(<span class="default"><a href="cat_1.html#K10">id</a> <font color="Maroon">c</font></span>)</span>,<span class="p2">(<span class="default"><a href="cat_1.html#K10">id</a> <font color="Maroon">d</font></span>)</span></span><a href="cat_2.html#K13" target="_self">]</a></span>
 
<b>by </b><i/>;<br/>
<a NAME="E2:60"/>
<span class="p1">(<span class="default"><a href="cat_2.html#K18" target="_self">pr2</a> <font color="Maroon">C</font>,<font color="Maroon">D</font></span>)</span> <a href="cat_2.html#K14" target="_self">.</a> <span class="p1">(<span class="default"><a href="cat_1.html#K10">id</a> <font color="Maroon">c</font></span>)</span>,<span class="p1">(<span class="default"><a href="cat_1.html#K10">id</a> <font color="Maroon">d</font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="cat_1.html#K10">id</a> <font color="Maroon">d</font>
 
<b>by </b><i><a class="ref" href="funct_3.html#D6">FUNCT_3:def 6</a></i>;<br/>
<b>hence </b><a NAME="E3:60"/>
<span class="p1">(<span class="default"><a href="cat_1.html#K12">Obj</a> <span class="p2">(<span class="default"><a href="cat_2.html#K18" target="_self">pr2</a> <font color="Maroon">C</font>,<font color="Maroon">D</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <span class="p1"><a href="cat_2.html#K12" target="_self">[</a><span class="default"><font color="Maroon">c</font>,<font color="Maroon">d</font></span><a href="cat_2.html#K12" target="_self">]</a></span> <a href="hidden.html#R1">=</a> <font color="Maroon">d</font>
 <b>by </b><i><a class="ref" href="cat_1.html#T103">CAT_1:103</a>, </i>;<br/>


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