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<b>let </b><font color="Maroon">Y</font> be  non <a href="struct_0.html#V3">empty</a> <a href="tdlat_3.html#V4" target="_self">extremally_disconnected</a> <a href="pre_topc.html#NM1">TopSpace</a>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="tdlat_1.html#K4">Domains_Lattice</a> <font color="Maroon">Y</font></span>)</span>, <font color="Maroon">b</font> be   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="tdlat_1.html#K4">Domains_Lattice</a> <font color="Maroon">Y</font></span>)</span>;<br/><b>let </b><font color="Maroon">A</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="tdlat_1.html#K1">Domains_of</a> <font color="Maroon">Y</font>, <font color="Maroon">B</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="tdlat_1.html#K1">Domains_of</a> <font color="Maroon">Y</font>;<br/>





<a NAME="E1:71"/><i><font color="Green">E21</font></i>: 
 <a href="tdlat_1.html#K4">Domains_Lattice</a> <font color="Maroon">Y</font> <a href="hidden.html#R1">=</a>  <a href="lattices.html#G3">LattStr</a>(# <span class="p1">(<span class="default"><a href="tdlat_1.html#K1">Domains_of</a> <font color="Maroon">Y</font></span>)</span>,<span class="p1">(<span class="default"><a href="tdlat_1.html#NK3" target="_self">D-Union</a> <font color="Maroon">Y</font></span>)</span>,<span class="p1">(<span class="default"><a href="tdlat_1.html#NK5" target="_self">D-Meet</a> <font color="Maroon">Y</font></span>)</span> #)
 
<b>by </b><i><a class="ref" href="tdlat_1.html#D4">TDLAT_1:def 4</a></i>;<br/>
<b>assume </b><a NAME="E2:71"/><i><font color="Green">E35</font></i>: 
( <font color="Maroon">a</font> <a href="hidden.html#R1">=</a> <font color="Maroon">A</font> &amp; <font color="Maroon">b</font> <a href="hidden.html#R1">=</a> <font color="Maroon">B</font> )
 ;<br/>

<b>hence </b><font color="Maroon">a</font> <a href="lattices.html#K3">"\/"</a> <font color="Maroon">b</font> = 
<span class="p1">(<span class="default"><a href="tdlat_1.html#NK3" target="_self">D-Union</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A</font>,<font color="Maroon">B</font>
<b>by </b><i><a class="ref" href="tdlat_3.html#D3" target="_self">Def3</a>, <a class="ref" href="lattices.html#D1">LATTICES:def 1</a></i>
<br/>.= 
<font color="Maroon">A</font> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">B</font>
<b>by </b><i/>
;<br/><br/>

<b>thus </b><font color="Maroon">a</font> <a href="lattices.html#K4">"/\"</a> <font color="Maroon">b</font> = 
<span class="p1">(<span class="default"><a href="tdlat_1.html#NK5" target="_self">D-Meet</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A</font>,<font color="Maroon">B</font>
<b>by </b><i><a class="ref" href="tdlat_3.html#D3" target="_self">Def3</a>, <a class="ref" href="tdlat_3.html#T17" target="_self">Th17</a>, <a class="ref" href="lattices.html#D2">LATTICES:def 2</a></i>
<br/>.= 
<font color="Maroon">A</font> <a href="xboole_0.html#K3">/\</a> <font color="Maroon">B</font>
<b>by </b><i/>
;<br/>


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