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<b>let </b><font color="Maroon">L</font> be   <a href="waybel_0.html#NM6">Semilattice</a>;<br/><b>let </b><font color="Maroon">S</font> be  non <a href="xboole_0.html#V1">empty</a> <a href="waybel_0.html#V13">upper</a> <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">L</font>;<br/>



<a NAME="E1:43"/>
( <font color="Maroon">S</font> is   <a href="waybel_0.html#NM4">Filter</a> of <font color="Maroon">L</font> iff  <a href="yellow_0.html#K5">subrelstr</a> <font color="Maroon">S</font> is <a href="yellow_0.html#V5">meet-inheriting</a> )
 
<b>by </b><i><a class="ref" href="waybel_0.html#T63">WAYBEL_0:63</a></i>;<br/>
<b>hence </b><a NAME="E2:43"/>
( <font color="Maroon">S</font> is   <a href="waybel_0.html#NM4">Filter</a> of <font color="Maroon">L</font> iff <font color="Maroon">S</font> is <a href="waybel23.html#V1" target="_self">meet-closed</a> )
 <b>by </b><i/>;<br/>


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