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<b>let </b><font color="Maroon">X</font> be  non <a href="struct_0.html#V3">empty</a> <a href="pre_topc.html#NM1">TopSpace</a>;<br/><b>let </b><font color="Maroon">A1</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font>;<br/><b>let </b><font color="Maroon">A2</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font>;<br/>





<b>assume </b><a NAME="E1:5"/>
( <font color="Maroon">A1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">A2</font> <a href="subset_1.html#K3">`</a>  or <font color="Maroon">A2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">A1</font> <a href="subset_1.html#K3">`</a>  )
 ;<br/>

<a NAME="E2:5"/><b>then </b>
( <font color="Maroon">A1</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A2</font> &amp; <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> <a href="hidden.html#R1">=</a>  <a href="pre_topc.html#K2">[#]</a> <font color="Maroon">X</font> )
 
<b>by </b><i><a class="ref" href="tdlat_1.html#T1">TDLAT_1:1</a>, <a class="ref" href="tdlat_1.html#T2">TDLAT_1:2</a></i>;<br/>
<b>hence </b><a NAME="E3:5"/>
<font color="Maroon">A1</font>,<font color="Maroon">A2</font> <a href="tsep_2.html#R1" target="_self">constitute_a_decomposition</a> 
 <b>by </b><i/>;<br/>


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