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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>thus </b><a NAME="E1:77"/>
( <font color="Maroon">A1</font>,<font color="Maroon">A2</font> <a href="connsp_1.html#R1">are_separated</a>  implies  ex <font color="Olive">B1</font>, <font color="Olive">B2</font> being  <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font> st <br/>( <font color="Olive">B1</font>,<font color="Olive">B2</font> <a href="tsep_1.html#R2" target="_self">are_weakly_separated</a>  &amp; <font color="Maroon">A1</font> <a href="tarski.html#R1">c=</a> <font color="Olive">B1</font> &amp; <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Olive">B2</font> &amp; <font color="Olive">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Olive">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> ) )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="77_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:77_1"/>
<font color="Maroon">A1</font>,<font color="Maroon">A2</font> <a href="connsp_1.html#R1">are_separated</a> 
 ;<br/>

<b>then consider </b><font color="Maroon">B1</font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font>, <font color="Maroon">B2</font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font><b> such that </b><br/><a NAME="E3:77_1"/><i><font color="Green">E17</font></i>: 
( <font color="Maroon">A1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> &amp; <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B2</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> )
 <b>and </b><br/><a NAME="E4:77_1"/><i><font color="Green">E27</font></i>: 
( <font color="Maroon">B1</font> is <a href="pre_topc.html#V3">open</a> &amp; <font color="Maroon">B2</font> is <a href="pre_topc.html#V3">open</a> )
 <b>by </b><i/>;<br/>
<b>take </b>
<font color="Maroon">B1</font>
;<br/>

<b>take </b>
<font color="Maroon">B2</font>
;<br/>

<b>thus </b><a NAME="E5:77_1"/>
( <font color="Maroon">B1</font>,<font color="Maroon">B2</font> <a href="tsep_1.html#R2" target="_self">are_weakly_separated</a>  &amp; <font color="Maroon">A1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> &amp; <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B2</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> )
 <b>by </b><i><a class="txt" href="tsep_1.html#E21"><i><font color="Green">Lemma55</font></i></a>, , </i>;<br/>


</div><b>end;</b></div>

<b>given </b><font color="Maroon">B1</font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font>, <font color="Maroon">B2</font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">X</font><b> such that </b><a NAME="E2:77"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">B1</font>,<font color="Maroon">B2</font> <a href="tsep_1.html#R2" target="_self">are_weakly_separated</a> 
 <b>and </b><br/><a NAME="E3:77"/><i><font color="Green">E30</font></i>: 
( <font color="Maroon">A1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> &amp; <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B2</font> )
 <b>and </b><br/><a NAME="E4:77"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font>
 ;<br/>

<a NAME="E5:77"/>
( <font color="Maroon">A1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A1</font> &amp; <font color="Maroon">A1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A2</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> )
 
<b>by </b><i>, <a class="ref" href="xboole_1.html#T17">XBOOLE_1:17</a>, <a class="ref" href="xboole_1.html#T26">XBOOLE_1:26</a></i>;<br/>
<a NAME="E6:77"/><b>then </b><i><font color="Green">E32</font></i>: 
( <font color="Maroon">A1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font></span>)</span> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A1</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font></span>)</span> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> )
 
<b>by </b><i><a class="ref" href="xboole_1.html#T19">XBOOLE_1:19</a></i>;<br/>
<a NAME="E7:77"/>
( <font color="Maroon">A1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> &amp; <font color="Maroon">A2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">A1</font> <a href="subset_1.html#K4">\/</a> <font color="Maroon">A2</font> )
 
<b>by </b><i><a class="ref" href="xboole_1.html#T7">XBOOLE_1:7</a></i>;<br/>
<a NAME="E8:77"/><b>then </b>
( <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A1</font> &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">A2</font> )
 
<b>by </b><i>, <a class="ref" href="xboole_1.html#T63">XBOOLE_1:63</a></i>;<br/>
<a NAME="E9:77"/><b>then </b>
( <span class="p1">(<span class="default"><font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font></span>)</span> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A1</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  &amp; <span class="p1">(<span class="default"><font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font></span>)</span> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  )
 
<b>by </b><i><a class="ref" href="xboole_0.html#D7">XBOOLE_0:def 7</a></i>;<br/>
<a NAME="E10:77"/><b>then </b><i><font color="Green">E33</font></i>: 
( <font color="Maroon">A1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  &amp; <font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  )
 
<b>by </b><i><a class="ref" href="tsep_1.html#T16" target="_self">Th16</a>, <a class="ref" href="xboole_1.html#T3">XBOOLE_1:3</a></i>;<br/>
<a NAME="E11:77"/>
( <font color="Maroon">A1</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B2</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B2</font> &amp; <font color="Maroon">A2</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B1</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B2</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B1</font> )
 
<b>by </b><i>, <a class="ref" href="xboole_1.html#T33">XBOOLE_1:33</a></i>;<br/>
<a NAME="E12:77"/><b>then </b><i><font color="Green">E34</font></i>: 
( <font color="Maroon">A1</font> <a href="subset_1.html#K7">\</a> <span class="p1">(<span class="default"><font color="Maroon">A1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">B2</font></span>)</span> <a href="tarski.html#R1">c=</a> <font color="Maroon">B1</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B2</font> &amp; <font color="Maroon">A2</font> <a href="subset_1.html#K7">\</a> <span class="p1">(<span class="default"><font color="Maroon">B1</font> <a href="subset_1.html#K9">/\</a> <font color="Maroon">A2</font></span>)</span> <a href="tarski.html#R1">c=</a> <font color="Maroon">B2</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B1</font> )
 
<b>by </b><i><a class="ref" href="xboole_1.html#T47">XBOOLE_1:47</a></i>;<br/>
<a NAME="E13:77"/>
<font color="Maroon">B1</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B2</font>,<font color="Maroon">B2</font> <a href="subset_1.html#K7">\</a> <font color="Maroon">B1</font> <a href="connsp_1.html#R1">are_separated</a> 
 
<b>by </b><i><a class="txt" href="tsep_1.html#E21"><i><font color="Green">Lemma55</font></i></a>, <a class="ref" href="tsep_1.html#T5" target="_self">Th5</a></i>;<br/>
<b>hence </b><a NAME="E14:77"/>
<font color="Maroon">A1</font>,<font color="Maroon">A2</font> <a href="connsp_1.html#R1">are_separated</a> 
 <b>by </b><i><a class="ref" href="tsep_1.html#T20" target="_self">Th20</a>, <a class="ref" href="tsep_1.html#D2" target="_self">Def2</a>, <a class="ref" href="connsp_1.html#T8">CONNSP_1:8</a></i>;<br/>


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