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<b>let </b><font color="Maroon" title="c1">FMT</font> be  non <a href="struct_0.html#V3" title="STRUCT_0:attr.3">empty</a>  <a href="fintopo2.html#L1" title="FINTOPO2:struct.1">FMT_Space_Str</a> ;<br/><b>let </b><font color="Maroon" title="c2">A</font> be   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c1">FMT</font>;<br/>



<b>assume </b><a NAME="E1:57"/>
<font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  is <a href="fintopo2.html#V4" title="FINTOPO2:attr.4">Fo_closed</a>
 ;<br/>

<a NAME="E2:57"/><b>then </b><i><font color="Green" title="E24">A1</font></i>: 
<font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </span>)</span> <a href="fintopo2.html#K9" title="FINTOPO2:func.9">^Fob</a> 
 
<b>by </b><i><a class="ref" href="fintopo2.html#D17" target="_self" title="FINTOPO2:def.17">Def17</a></i>;<br/>
<span class="p1">(<span class="default"><font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </span>)</span> <a href="fintopo2.html#K9" title="FINTOPO2:func.9">^Fob</a>  = 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </span>)</span> <a href="fintopo2.html#K10" title="FINTOPO2:func.10">^Foi</a> </span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
<b>by </b><i><a class="ref" href="fintopo2.html#T39" target="_self" title="FINTOPO2:th.39">Th39</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c2">A</font> <a href="fintopo2.html#K10" title="FINTOPO2:func.10">^Foi</a> </span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 

;<br/>
<b>then </b><font color="Maroon" title="c2">A</font> = 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c2">A</font> <a href="fintopo2.html#K10" title="FINTOPO2:func.10">^Foi</a> </span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> </span>)</span> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
<b>by </b><i><a class="txt" href="fintopo2.html#E2:57"><i><font color="Green" title="E24">A1</font></i></a></i>
<br/>.= 
<font color="Maroon" title="c2">A</font> <a href="fintopo2.html#K10" title="FINTOPO2:func.10">^Foi</a> 

;<br/>
<b>hence </b><a NAME="E5:57"/>
<font color="Maroon" title="c2">A</font> is <a href="fintopo2.html#V3" title="FINTOPO2:attr.3">Fo_open</a>
 <b>by </b><i><a class="ref" href="fintopo2.html#D16" target="_self" title="FINTOPO2:def.16">Def16</a></i>;<br/>


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