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<b>consider </b><font color="Maroon">c<sub>1</sub></font> being  non <a href="struct_0.html#V3">empty</a> <a href="tdlat_3.html#V1">discrete</a> <a href="group_1.html#V6">finite</a> <a href="realset2.html#V3">trivial</a> <a href="orders_2.html#V2">reflexive</a> <a href="waybel_9.html#V1">strict</a>  <a href="waybel_9.html#L1">TopRelStr</a> ;<br/>
<b>take </b>
<font color="Maroon">c<sub>1</sub></font>
;<br/>

<b>thus </b><a NAME="E2:23_1_1"/>
( <font color="Maroon">c<sub>1</sub></font> is <a href="realset2.html#V3">trivial</a> &amp; <font color="Maroon">c<sub>1</sub></font> is <a href="lattice3.html#V3">complete</a> &amp; <font color="Maroon">c<sub>1</sub></font> is <a href="waybel_9.html#V1">strict</a> &amp; not <font color="Maroon">c<sub>1</sub></font> is <a href="struct_0.html#V3">empty</a> )
 ;<br/>

<b>let </b><font color="Maroon">c<sub>2</sub></font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font>; <i><font color="Red">:: according to </font></i><a class="ref" href="waybel11.html#D5" target="_self">WAYBEL11:def 5</a><br/>

<b>thus </b><a NAME="E3:23_1_1"/>
( <font color="Maroon">c<sub>2</sub></font> is <a href="pre_topc.html#V3">open</a> iff <font color="Maroon">c<sub>2</sub></font> is <a href="waybel_0.html#V13">upper</a> )
 <b>by </b><i><a class="ref" href="tdlat_3.html#T17">TDLAT_3:17</a></i>;<br/>


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