<?xml version="1.0"?>
<div class="add">

<a NAME="E1:72_1_1"/>
( <font color="Maroon" title="c2">A</font> is <a href="pre_topc.html#V3" title="PRE_TOPC:attr.3">open</a> &amp; <font color="Maroon" title="c2">A</font> is <a href="pre_topc.html#V4" title="PRE_TOPC:attr.4">closed</a> )
 
<b>by </b><i><a class="ref" href="tdlat_3.html#T18" title="TDLAT_3:th.18">TDLAT_3:18</a>, <a class="ref" href="tdlat_3.html#T17" title="TDLAT_3:th.17">TDLAT_3:17</a></i>;<br/>
<b>hence </b><a NAME="E2:72_1_1"/>
 <a href="tops_1.html#K2" title="TOPS_1:func.2">Fr</a> <font color="Maroon" title="c2">A</font> is <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>
 <b>by </b><i><a class="ref" href="topgen_1.html#T16" target="_self" title="TOPGEN_1:th.16">Th16</a></i>;<br/>


</div>
