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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">X0</font> be  non <a href="struct_0.html#V3">empty</a>  <a href="pre_topc.html#M1">SubSpace</a> of <font color="Maroon">X</font>;<br/>



<a NAME="E1:27"/>
<font color="Maroon">X0</font> is    <a href="pre_topc.html#M1">SubSpace</a> of <font color="Maroon">X0</font>
 
<b>by </b><i><a class="ref" href="tsep_1.html#T2">TSEP_1:2</a></i>;<br/>
<b>hence </b><a NAME="E2:27"/>
<font color="Maroon">X0</font> <a href="tsep_1.html#K1">union</a> <font color="Maroon">X0</font> <a href="hidden.html#R1">=</a>  <a href="pre_topc.html#G1">TopStruct</a>(# the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">X0</font>,the <a href="pre_topc.html#U1">topology</a> of <font color="Maroon">X0</font> #)
 <b>by </b><i><a class="ref" href="tsep_1.html#T23">TSEP_1:23</a></i>;<br/>


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