<?xml version="1.0"?>
<div><span class="kw">theorem </span><a NAME="T12"><span class="comment"><font color="firebrick">:: TOPGEN_4:12</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">T</font> being    <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a> <br/>  for <font color="Olive" title="b2">F</font> being   <a href="setfam_1.html#NM1" title="SETFAM_1:NM.1">Subset-Family</a> of <font color="Olive" title="b1">T</font>  st <font color="Olive" title="b2">F</font> is  <a href="topgen_4.html#V3" title="TOPGEN_4:attr.3">closed_for_countable_unions</a>  holds <br/> <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a>  <a href="tarski.html#R2" title="TARSKI:pred.2">in</a> <font color="Olive" title="b2">F</font></div></div>
