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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="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/>



<b>reconsider </b><font color="Maroon">A0</font> = <font color="Maroon">A</font>, <font color="Maroon">B0</font> = <font color="Maroon">B</font> as    <a href="subset_1.html#M1">Element</a> of  <a href="tdlat_1.html#K5">Closed_Domains_of</a> <font color="Maroon">Y</font> <b>by </b><i/>;<br/>
<a NAME="E2:70"/>
( <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> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="tdlat_1.html#NK9" target="_self">CLD-Union</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A0</font>,<font color="Maroon">B0</font> &amp; <span class="p1">(<span class="default"><a href="tdlat_1.html#NK9" target="_self">CLD-Union</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A0</font>,<font color="Maroon">B0</font> <a href="hidden.html#R1">=</a> <font color="Maroon">A0</font> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">B0</font> )
 
<b>by </b><i>, <a class="ref" href="tdlat_1.html#D6">TDLAT_1:def 6</a></i>;<br/>
<b>hence </b><a NAME="E3:70"/>
<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> <a href="hidden.html#R1">=</a> <font color="Maroon">A</font> <a href="xboole_0.html#K2">\/</a> <font color="Maroon">B</font>
 ;<br/>

<b>reconsider </b><font color="Maroon">A0</font> = <font color="Maroon">A</font>, <font color="Maroon">B0</font> = <font color="Maroon">B</font> as    <a href="subset_1.html#M1">Element</a> of  <a href="tdlat_1.html#K9">Open_Domains_of</a> <font color="Maroon">Y</font> <b>by </b><i><a class="ref" href="tdlat_3.html#T15" target="_self">Th15</a></i>;<br/>
<a NAME="E5:70"/>
( <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> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="tdlat_1.html#NK17" target="_self">OPD-Meet</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A0</font>,<font color="Maroon">B0</font> &amp; <span class="p1">(<span class="default"><a href="tdlat_1.html#NK17" target="_self">OPD-Meet</a> <font color="Maroon">Y</font></span>)</span> <a href="binop_1.html#K1">.</a> <font color="Maroon">A0</font>,<font color="Maroon">B0</font> <a href="hidden.html#R1">=</a> <font color="Maroon">A0</font> <a href="xboole_0.html#K3">/\</a> <font color="Maroon">B0</font> )
 
<b>by </b><i>, <a class="ref" href="tdlat_1.html#D11">TDLAT_1:def 11</a></i>;<br/>
<b>hence </b><a NAME="E6:70"/>
<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> <a href="hidden.html#R1">=</a> <font color="Maroon">A</font> <a href="xboole_0.html#K3">/\</a> <font color="Maroon">B</font>
 ;<br/>


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