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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#L1">TopStruct</a> ;<br/><b>let </b><font color="Maroon">A</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">T</font>;<br/><b>let </b><font color="Maroon">p</font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">T</font>;<br/>





<b>thus </b><a NAME="E1:40"/>
( <font color="Maroon">p</font> <a href="hidden.html#R2">in</a>  <a href="pre_topc.html#K4">Cl</a> <font color="Maroon">A</font> implies for <font color="Olive">K</font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">p</font><br/> for <font color="Olive">Q</font> being  <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">T</font>  st <font color="Olive">Q</font> <a href="hidden.html#R2">in</a> <font color="Olive">K</font> holds <br/><font color="Maroon">A</font> <a href="xboole_0.html#NR5" target="_self">meets</a> <font color="Olive">Q</font> )
 <b>by </b><i/>;<br/>

<b>assume </b><a NAME="E2:40"/>
for <font color="Olive">K</font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">p</font><br/> for <font color="Olive">Q</font> being  <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">T</font>  st <font color="Olive">Q</font> <a href="hidden.html#R2">in</a> <font color="Olive">K</font> holds <br/><font color="Maroon">A</font> <a href="xboole_0.html#NR5" target="_self">meets</a> <font color="Olive">Q</font>
 ;<br/>

<a NAME="E3:40"/><b>then </b>
 ex <font color="Olive">K</font> being   <a href="yellow_8.html#M1">Basis</a> of <font color="Maroon">p</font> st <br/>for <font color="Olive">Q</font> being  <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">T</font>  st <font color="Olive">Q</font> <a href="hidden.html#R2">in</a> <font color="Olive">K</font> holds <br/><font color="Maroon">A</font> <a href="xboole_0.html#NR5" target="_self">meets</a> <font color="Olive">Q</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:40"/>
<font color="Maroon">p</font> <a href="hidden.html#R2">in</a>  <a href="pre_topc.html#K4">Cl</a> <font color="Maroon">A</font>
 <b>by </b><i/>;<br/>


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