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<b>let </b><font color="Maroon">L</font> be    <a href="orders_2.html#L1">RelStr</a> ;<br/><b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/>



<a NAME="E1:16"/>
(  <a href="yellow_0.html#R2">ex_inf_of</a> <font color="Maroon">X</font>,<font color="Maroon">L</font> iff  <a href="yellow_0.html#R2">ex_inf_of</a> <font color="Maroon">X</font>,<span class="p1">(<span class="default"><font color="Maroon">L</font> <a href="yellow_7.html#NK1" target="_self">opp</a> </span>)</span> <a href="lattice3.html#K7">~</a>  )
 
<b>by </b><i><a class="ref" href="yellow_0.html#T14">YELLOW_0:14</a></i>;<br/>
<b>hence </b><a NAME="E2:16"/>
(  <a href="yellow_0.html#R1">ex_sup_of</a> <font color="Maroon">X</font>,<font color="Maroon">L</font> <a href="yellow_7.html#NK1" target="_self">opp</a>  iff  <a href="yellow_0.html#R2">ex_inf_of</a> <font color="Maroon">X</font>,<font color="Maroon">L</font> )
 <b>by </b><i/>;<br/>


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