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<b>let </b><font color="Maroon" title="c1">TS</font> be   <a href="pre_topc.html#NM1" title="PRE_TOPC:NM.1">TopSpace</a>;<br/><b>let </b><font color="Maroon" title="c2">GX</font> be    <a href="pre_topc.html#L1" title="PRE_TOPC:struct.1">TopStruct</a> ;<br/><b>let </b><font color="Maroon" title="c3">P</font> be   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c1">TS</font>;<br/><b>let </b><font color="Maroon" title="c4">R</font> be   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c2">GX</font>;<br/>







<div><b>hereby </b>
<div class="add"><b>assume </b><b>that </b><br/><a NAME="E1:106_1"/><i><font color="Green" title="E65">A1</font></i>: 
<font color="Maroon" title="c4">R</font> is <a href="pre_topc.html#V3" title="PRE_TOPC:attr.3">open</a>
 <b>and </b><br/><a NAME="E2:106_1"/><i><font color="Green" title="E66">A2</font></i>: 
<font color="Maroon" title="c4">R</font> is <a href="tops_1.html#V4" title="TOPS_1:attr.4">condensed</a>
 ;<br/><a NAME="E3:106_1"/><i><font color="Green" title="E67">A3</font></i>: 
<font color="Maroon" title="c4">R</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <font color="Maroon" title="c4">R</font>
 <b>by </b><i><a class="txt" href="tops_1.html#E1:106_1"><i><font color="Green" title="E65">A1</font></i></a>, <a class="ref" href="tops_1.html#T55" target="_self" title="TOPS_1:th.55">Th55</a></i>;<br/><a NAME="E4:106_1"/><i><font color="Green" title="E68">A4</font></i>: 
(  <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c4">R</font></span>)</span> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Maroon" title="c4">R</font> &amp; <font color="Maroon" title="c4">R</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <span class="p1">(<span class="default"><a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <font color="Maroon" title="c4">R</font></span>)</span> )
 <b>by </b><i><a class="txt" href="tops_1.html#E2:106_1"><i><font color="Green" title="E66">A2</font></i></a>, <a class="ref" href="tops_1.html#D6" target="_self" title="TOPS_1:def.6">Def6</a></i>;<br/><a NAME="E5:106_1"/>
<font color="Maroon" title="c4">R</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c4">R</font>
 <b>by </b><i><a class="ref" href="pre_topc.html#T48" title="PRE_TOPC:th.48">PRE_TOPC:48</a></i>;<br/><a NAME="E6:106_1"/><b>then </b>
<font color="Maroon" title="c4">R</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c4">R</font></span>)</span>
 <b>by </b><i><a class="txt" href="tops_1.html#E3:106_1"><i><font color="Green" title="E67">A3</font></i></a>, <a class="ref" href="tops_1.html#T48" target="_self" title="TOPS_1:th.48">Th48</a></i>;<br/><a NAME="E7:106_1"/><b>then </b>
 <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c4">R</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c4">R</font>
 <b>by </b><i><a class="txt" href="tops_1.html#E4:106_1"><i><font color="Green" title="E68">A4</font></i></a>, <a class="ref" href="xboole_0.html#D10" title="XBOOLE_0:def.10">XBOOLE_0:def 10</a></i>;<br/><b>hence </b><a NAME="E8:106_1"/>
<font color="Maroon" title="c4">R</font> is <a href="tops_1.html#V6" title="TOPS_1:attr.6">open_condensed</a>
 <b>by </b><i><a class="ref" href="tops_1.html#D8" target="_self" title="TOPS_1:def.8">Def8</a></i>;<br/></div>
<b>end;</b></div>

<b>assume </b><a NAME="E2:106"/><i><font color="Green" title="E65">A5</font></i>: 
<font color="Maroon" title="c3">P</font> is <a href="tops_1.html#V6" title="TOPS_1:attr.6">open_condensed</a>
 ;<br/>

<a NAME="E3:106"/><b>then </b>
(  <a href="tops_1.html#K2" title="TOPS_1:func.2">Fr</a> <font color="Maroon" title="c3">P</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="tops_1.html#K2" title="TOPS_1:func.2">Fr</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c3">P</font></span>)</span> &amp;  <a href="tops_1.html#K2" title="TOPS_1:func.2">Fr</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c3">P</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c3">P</font></span>)</span> <a href="subset_1.html#K7" title="SUBSET_1:func.7">\</a> <font color="Maroon" title="c3">P</font> )
 
<b>by </b><i><a class="ref" href="tops_1.html#T104" target="_self" title="TOPS_1:th.104">Th104</a></i>;<br/>
<a NAME="E4:106"/><b>then </b><i><font color="Green" title="E66">A6</font></i>: 
<font color="Maroon" title="c3">P</font> is <a href="pre_topc.html#V3" title="PRE_TOPC:attr.3">open</a>
 
<b>by </b><i><a class="ref" href="tops_1.html#T76" target="_self" title="TOPS_1:th.76">Th76</a></i>;<br/>
<a NAME="E5:106"/><i><font color="Green" title="E67">A7</font></i>: 
<font color="Maroon" title="c3">P</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <span class="p1">(<span class="default"><a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <font color="Maroon" title="c3">P</font></span>)</span>
 
<b>by </b><i><a class="txt" href="tops_1.html#E2:106"><i><font color="Green" title="E65">A5</font></i></a>, <a class="ref" href="tops_1.html#D8" target="_self" title="TOPS_1:def.8">Def8</a></i>;<br/>
<a NAME="E6:106"/>
 <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <font color="Maroon" title="c3">P</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">P</font>
 
<b>by </b><i><a class="txt" href="tops_1.html#E4:106"><i><font color="Green" title="E66">A6</font></i></a>, <a class="ref" href="tops_1.html#T55" target="_self" title="TOPS_1:th.55">Th55</a></i>;<br/>
<a NAME="E7:106"/><b>then </b>
<font color="Maroon" title="c3">P</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="pre_topc.html#K2" title="PRE_TOPC:func.2">Cl</a> <span class="p1">(<span class="default"><a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <font color="Maroon" title="c3">P</font></span>)</span>
 
<b>by </b><i><a class="ref" href="pre_topc.html#T48" title="PRE_TOPC:th.48">PRE_TOPC:48</a></i>;<br/>
<b>hence </b><a NAME="E8:106"/>
( <font color="Maroon" title="c3">P</font> is <a href="pre_topc.html#V3" title="PRE_TOPC:attr.3">open</a> &amp; <font color="Maroon" title="c3">P</font> is <a href="tops_1.html#V4" title="TOPS_1:attr.4">condensed</a> )
 <b>by </b><i><a class="txt" href="tops_1.html#E5:106"><i><font color="Green" title="E67">A7</font></i></a>, <a class="ref" href="tops_1.html#D6" target="_self" title="TOPS_1:def.6">Def6</a></i>;<br/>


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