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<a NAME="E1:27_1_1"/>
<font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="filter_0.html#K2">&lt;.</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="filter_0.html#K2">.)</a></span>
 
;<br/>
<a NAME="E2:27_1_1"/><b>then </b>
<span class="p1"><a href="filter_0.html#K2">&lt;.</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="filter_0.html#K2">.)</a></span> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <font color="Olive">b<sub>1</sub></font> where B is    <a href="filter_0.html#M1">Filter</a> of <font color="Maroon">c<sub>1</sub></font> : <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Olive">b<sub>1</sub></font> </span>}</span> 
 
;<br/>
<b>hence </b><a NAME="E3:27_1_1"/>
not  <a href="openlatt.html#K10" target="_self">SF_have</a> <font color="Maroon">c<sub>2</sub></font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/>


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