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<b>let </b><font color="Maroon">T</font> be  non <a href="struct_0.html#V3">empty</a> <a href="pre_topc.html#NM1">TopSpace</a>;<br/>

<b>reconsider </b><font color="Maroon">F</font> = <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><span class="p2">(<span class="default"><a href="pre_topc.html#K2">[#]</a> <font color="Maroon">T</font></span>)</span></span><a href="domain_1.html#K6">}</a></span> as   <a href="struct_0.html#NM3">Subset-Family</a> of <font color="Maroon">T</font> ;<br/>
<a NAME="E2:61"/><i><font color="Green">E37</font></i>: 
<font color="Maroon">F</font> is <a href="tops_2.html#V2">closed</a>
 
<b>by </b><i/>;<br/>
<a NAME="E3:61"/>
 <a href="pre_topc.html#K2">[#]</a> <font color="Maroon">T</font> <a href="hidden.html#R1">=</a>  <a href="setfam_1.html#K5">union</a> <font color="Maroon">F</font>
 
<b>by </b><i><a class="ref" href="zfmisc_1.html#T31">ZFMISC_1:31</a></i>;<br/>
<b>hence </b><a NAME="E4:61"/>
 <a href="pre_topc.html#K2">[#]</a> <font color="Maroon">T</font> is <a href="topgen_4.html#V5" target="_self">F_sigma</a>
 <b>by </b><i>, </i>;<br/>


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