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

<b>consider </b><font color="Maroon">c<sub>2</sub></font> being  <a href="xboole_0.html#V1">empty</a> <a href="struct_0.html#NM3">Subset-Family</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>
<a NAME="E2:36_1_1"/>
<font color="Maroon">c<sub>2</sub></font> is <a href="tops_2.html#V1">open</a>
 
;<br/>
<b>hence </b><a NAME="E3:36_1_1"/>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM3">Subset-Family</a> of <font color="Maroon">c<sub>1</sub></font> st <br/>( <font color="Olive">b<sub>1</sub></font> is <a href="card_4.html#V1">countable</a> &amp; <font color="Olive">b<sub>1</sub></font> is <a href="tops_2.html#V1">open</a> &amp; <font color="Olive">b<sub>1</sub></font> is <a href="tops_2.html#V2">closed</a> )
 ;<br/>


</div>
