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<b>let </b><font color="Maroon" title="c1">FT</font> be  non <a href="struct_0.html#V2" title="STRUCT_0:attr.2">empty</a>  <a href="orders_2.html#L1" title="ORDERS_2:struct.1">RelStr</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">FT</font>;<br/>



<b>assume </b><b>that </b><br/><a NAME="E1:28"/><i><font color="Green" title="E16">A1</font></i>: 
( <font color="Maroon" title="c1">FT</font> is <a href="orders_2.html#V3" title="ORDERS_2:attr.3">reflexive</a> &amp; <font color="Maroon" title="c1">FT</font> is <a href="fin_topo.html#V1" title="FIN_TOPO:attr.1">symmetric</a> )
 <b>and </b><br/><a NAME="E2:28"/><i><font color="Green" title="E17">A2</font></i>: 
<font color="Maroon" title="c1">FT</font> is <a href="fintopo6.html#V1" title="FINTOPO6:attr.1">connected</a>
 <b>and </b><br/><a NAME="E3:28"/><i><font color="Green" title="E18">A3</font></i>: 
<font color="Maroon" title="c2">A</font> <a href="hidden.html#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 <b>and </b><br/><a NAME="E4:28"/><i><font color="Green" title="E19">A4</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#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 ;<br/>

<a NAME="E5:28"/><i><font color="Green" title="E20">A5</font></i>: 
 <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K1" title="STRUCT_0:func.1">{}</a> <font color="Maroon" title="c1">FT</font>
 
;<br/>
<a NAME="E6:28"/>
<font color="Maroon" title="c2">A</font> <a href="subset_1.html#K4" title="SUBSET_1:func.4">\/</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="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K2" title="STRUCT_0:func.2">[#]</a> <font color="Maroon" title="c1">FT</font>
 
<b>by </b><i><a class="ref" href="xboole_1.html#T45" title="XBOOLE_1:th.45">XBOOLE_1:45</a></i>;<br/>
<a NAME="E7:28"/><b>then </b><i><font color="Green" title="E21">A6</font></i>: 
not <font color="Maroon" title="c2">A</font>,<font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  <a href="fintopo4.html#R1" title="FINTOPO4:pred.1">are_separated</a> 
 
<b>by </b><i><a class="txt" href="fintopo6.html#E2:28"><i><font color="Green" title="E17">A2</font></i></a>, <a class="txt" href="fintopo6.html#E3:28"><i><font color="Green" title="E18">A3</font></i></a>, <a class="txt" href="fintopo6.html#E4:28"><i><font color="Green" title="E19">A4</font></i></a>, <a class="txt" href="fintopo6.html#E5:28"><i><font color="Green" title="E20">A5</font></i></a>, <a class="ref" href="fintopo6.html#T5" target="_self" title="FINTOPO6:th.5">Th5</a>, <a class="ref" href="xboole_1.html#T79" title="XBOOLE_1:th.79">XBOOLE_1:79</a></i>;<br/>
<div><i><font color="Green" title="E22">A7</font></i>: <a class="txt" onclick="hs2(this)" href="javascript:()" title="28_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:28_1"/>
<font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K9" title="FIN_TOPO:func.9">^b</a>  <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
 ;<br/><b>then consider </b><font color="Maroon" title="c3">x</font> being    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> <b> such that </b><br/><a NAME="E3:28_1"/><i><font color="Green" title="E23">A8</font></i>: 
( <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K9" title="FIN_TOPO:func.9">^b</a>  &amp; <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  )
 <b>by </b><i><a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><b>reconsider </b><font color="Maroon" title="c4">x</font> = <font color="Maroon" title="c3">x</font> as   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">FT</font> <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_1"><i><font color="Green" title="E23">A8</font></i></a></i>;<br/><a NAME="E5:28_1"/>
 <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c4">x</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_1"><i><font color="Green" title="E23">A8</font></i></a>, <a class="ref" href="fin_topo.html#T13" title="FIN_TOPO:th.13">FIN_TOPO:13</a></i>;<br/><b>then consider </b><font color="Maroon" title="c5">y</font> being    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> <b> such that </b><br/><a NAME="E7:28_1"/><i><font color="Green" title="E24">A9</font></i>: 
( <font color="Maroon" title="c5">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c4">x</font> &amp; <font color="Maroon" title="c5">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> )
 <b>by </b><i><a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><b>reconsider </b><font color="Maroon" title="c6">y</font> = <font color="Maroon" title="c5">y</font> as   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">FT</font> <b>by </b><i><a class="txt" href="fintopo6.html#E7:28_1"><i><font color="Green" title="E24">A9</font></i></a></i>;<br/><a NAME="E9:28_1"/><i><font color="Green" title="E25">A10</font></i>: 
<font color="Maroon" title="c4">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c6">y</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E1:28"><i><font color="Green" title="E16">A1</font></i></a>, <a class="txt" href="fintopo6.html#E7:28_1"><i><font color="Green" title="E24">A9</font></i></a>, <a class="ref" href="fin_topo.html#D15" title="FIN_TOPO:def.15">FIN_TOPO:def 15</a></i>;<br/><a NAME="E10:28_1"/>
<font color="Maroon" title="c6">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c6">y</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E1:28"><i><font color="Green" title="E16">A1</font></i></a>, <a class="ref" href="fin_topo.html#D4" title="FIN_TOPO:def.4">FIN_TOPO:def 4</a></i>;<br/><a NAME="E11:28_1"/><b>then </b><i><font color="Green" title="E26">A11</font></i>: 
 <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c6">y</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E7:28_1"><i><font color="Green" title="E24">A9</font></i></a>, <a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><a NAME="E12:28_1"/>
 <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c6">y</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_1"><i><font color="Green" title="E23">A8</font></i></a>, <a class="txt" href="fintopo6.html#E9:28_1"><i><font color="Green" title="E25">A10</font></i></a>, <a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><a NAME="E13:28_1"/><b>then </b>
<font color="Maroon" title="c6">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K5" title="FIN_TOPO:func.5">^delta</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E11:28_1"><i><font color="Green" title="E26">A11</font></i></a></i>;<br/><b>hence </b><a NAME="E14:28_1"/>
<font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K6" title="FIN_TOPO:func.6">^deltai</a>  <a href="hidden.html#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E7:28_1"><i><font color="Green" title="E24">A9</font></i></a>, <a class="ref" href="xboole_0.html#D3" title="XBOOLE_0:def.3">XBOOLE_0:def 3</a></i>;<br/></div><b>end;</b></div>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="28_2"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:28_2"/>
<font color="Maroon" title="c2">A</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</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="fin_topo.html#K9" title="FIN_TOPO:func.9">^b</a> 
 ;<br/><b>then consider </b><font color="Maroon" title="c3">x</font> being    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> <b> such that </b><br/><a NAME="E3:28_2"/><i><font color="Green" title="E23">A12</font></i>: 
( <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</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="fin_topo.html#K9" title="FIN_TOPO:func.9">^b</a>  &amp; <font color="Maroon" title="c3">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> )
 <b>by </b><i><a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><b>reconsider </b><font color="Maroon" title="c4">x</font> = <font color="Maroon" title="c3">x</font> as   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">FT</font> <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_2"><i><font color="Green" title="E23">A12</font></i></a></i>;<br/><a NAME="E5:28_2"/><i><font color="Green" title="E24">A13</font></i>: 
 <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c4">x</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_2"><i><font color="Green" title="E23">A12</font></i></a>, <a class="ref" href="fin_topo.html#T13" title="FIN_TOPO:th.13">FIN_TOPO:13</a></i>;<br/><a NAME="E6:28_2"/>
<font color="Maroon" title="c4">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c4">x</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E1:28"><i><font color="Green" title="E16">A1</font></i></a>, <a class="ref" href="fin_topo.html#D4" title="FIN_TOPO:def.4">FIN_TOPO:def 4</a></i>;<br/><a NAME="E7:28_2"/><b>then </b>
 <a href="fin_topo.html#K1" title="FIN_TOPO:func.1">U_FT</a> <font color="Maroon" title="c4">x</font> <a href="xboole_0.html#NR5" title="XBOOLE_0:NR.5">meets</a> <font color="Maroon" title="c2">A</font>
 <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_2"><i><font color="Green" title="E23">A12</font></i></a>, <a class="ref" href="xboole_0.html#T3" title="XBOOLE_0:th.3">XBOOLE_0:3</a></i>;<br/><a NAME="E8:28_2"/><b>then </b>
<font color="Maroon" title="c4">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K5" title="FIN_TOPO:func.5">^delta</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E5:28_2"><i><font color="Green" title="E24">A13</font></i></a></i>;<br/><b>hence </b><a NAME="E9:28_2"/>
<font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K6" title="FIN_TOPO:func.6">^deltai</a>  <a href="hidden.html#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E3:28_2"><i><font color="Green" title="E23">A12</font></i></a>, <a class="ref" href="xboole_0.html#D3" title="XBOOLE_0:def.3">XBOOLE_0:def 3</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E10:28"/>
<font color="Maroon" title="c2">A</font> <a href="fin_topo.html#K6" title="FIN_TOPO:func.6">^deltai</a>  <a href="hidden.html#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 <b>by </b><i><a class="txt" href="fintopo6.html#E7:28"><i><font color="Green" title="E21">A6</font></i></a>, <a class="txt" href="fintopo6.html#E8:28"><i><font color="Green" title="E22">A7</font></i></a>, <a class="ref" href="fintopo4.html#D1" title="FINTOPO4:def.1">FINTOPO4:def 1</a></i>;<br/>


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