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<b>reconsider </b><font color="Maroon">c<sub>3</sub></font> = <font color="Maroon">c<sub>2</sub></font> as  non <a href="xboole_0.html#V1">empty</a> <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="lattice2.html#K1">.:</a> </span>)</span> ;<br/>
<a NAME="E2:32_1_1"/>
( not  <a href="filter_2.html#K8" target="_self">.:</a> <font color="Maroon">c<sub>3</sub></font> is <a href="xboole_0.html#V1">empty</a> &amp;  <a href="filter_2.html#K11" target="_self">.:</a> <font color="Maroon">c<sub>2</sub></font> is    <a href="lattice4.html#M2">ClosedSubset</a> of <font color="Maroon">c<sub>1</sub></font> )
 
;<br/>
<b>hence </b><a NAME="E3:32_1_1"/>
 <a href="filter_2.html#K8" target="_self">.:</a> <font color="Maroon">c<sub>2</sub></font> is  non <a href="xboole_0.html#V1">empty</a>  <a href="lattice4.html#M2">ClosedSubset</a> of <font color="Maroon">c<sub>1</sub></font>
 ;<br/>


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