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<span class="kw">consider </span><font color="Maroon" title="c2">F</font> being   <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>  <a href="struct_0.html#NM3" title="STRUCT_0:NM.3">Subset-Family</a> of <font color="Maroon" title="c1">T</font>;<br/>
<a NAME="E2:36_1_1"/>
<font color="Maroon" title="c2">F</font> is  <a href="tops_2.html#V1" title="TOPS_2:attr.1">open</a> 
 
;<br/>
<span class="kw">hence </span><a NAME="E3:36_1_1"/>
 ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM3" title="STRUCT_0:NM.3">Subset-Family</a> of <font color="Maroon" title="c1">T</font> st <br/>( <font color="Olive">b<sub>1</sub></font> is  <a href="card_3.html#V4" title="CARD_3:attr.4">countable</a>  &amp; <font color="Olive">b<sub>1</sub></font> is  <a href="tops_2.html#V1" title="TOPS_2:attr.1">open</a>  &amp; <font color="Olive">b<sub>1</sub></font> is  <a href="tops_2.html#V2" title="TOPS_2:attr.2">closed</a>  )
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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