<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">L</font> be  <a href="lattice3.html#V4">complete</a> <a href="lattices.html#NM1">Lattice</a>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>



<b>assume </b><a NAME="E1:33"/>
<font color="Maroon">a</font> is <a href="lattice6.html#V4" target="_self">completely-join-irreducible</a>
 ;<br/>

<a NAME="E2:33"/><b>then </b><i><font color="Green">E24</font></i>: 
 <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">a</font>
 
<b>by </b><i/>;<br/>
<b>set </b><font color="Maroon">X</font> = <span class="p1">{<span class="default"> <font color="Olive">x</font> where <font color="Olive">x</font> is   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font> : ( <font color="Olive">x</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; <font color="Olive">x</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">a</font> ) </span>}</span> ;<br/>
<a NAME="E3:33"/><i><font color="Green">E31</font></i>: 
 <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font>
 
<b>by </b><i/>;<br/>
<a NAME="E4:33"/><i><font color="Green">E32</font></i>: 
for <font color="Olive">c</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>  st  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="lattices.html#R3">[=</a> <font color="Olive">c</font> &amp; <font color="Olive">c</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; not <font color="Olive">c</font> <a href="hidden.html#R1">=</a> <font color="Maroon">a</font> holds <br/><font color="Olive">c</font> <a href="hidden.html#R1">=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="33_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">c</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>

<b>assume </b><a NAME="E1:33_1"/><i><font color="Green">E34</font></i>: 
(  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">c</font> &amp; <font color="Maroon">c</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> )
 ;<br/>

<b>assume </b><a NAME="E2:33_1"/>
<font color="Maroon">c</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">a</font>
 ;<br/>

<a NAME="E3:33_1"/><b>then </b>
<font color="Maroon">c</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <font color="Olive">x</font> where <font color="Olive">x</font> is   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font> : ( <font color="Olive">x</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; <font color="Olive">x</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">a</font> ) </span>}</span> 
 
<b>by </b><i/>;<br/>
<a NAME="E4:33_1"/><b>then </b>
<font color="Maroon">c</font> <a href="lattices.html#R3">[=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font>
 
<b>by </b><i><a class="ref" href="lattice3.html#T38">LATTICE3:38</a></i>;<br/>
<b>hence </b><a NAME="E5:33_1"/>
<font color="Maroon">c</font> <a href="hidden.html#R1">=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font>
 <b>by </b><i>, <a class="ref" href="lattices.html#T26">LATTICES:26</a></i>;<br/>


</div><b>end;</b></div>
<a NAME="E5:33"/>
for <font color="Olive">c</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>  st <font color="Olive">c</font> <a href="lattice6.html#NR2" target="_self">is-lower-neighbour-of</a> <font color="Maroon">a</font> holds <br/><font color="Olive">c</font> <a href="hidden.html#R1">=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="33_2"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">c</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>

<b>assume </b><a NAME="E1:33_2"/><i><font color="Green">E35</font></i>: 
<font color="Maroon">c</font> <a href="lattice6.html#NR2" target="_self">is-lower-neighbour-of</a> <font color="Maroon">a</font>
 ;<br/>

<a NAME="E2:33_2"/><b>then </b>
( <font color="Maroon">a</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c</font> &amp; <font color="Maroon">c</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; ( for <font color="Olive">d</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>  st <font color="Maroon">c</font> <a href="lattices.html#R3">[=</a> <font color="Olive">d</font> &amp; <font color="Olive">d</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; not <font color="Olive">d</font> <a href="hidden.html#R1">=</a> <font color="Maroon">c</font> holds <br/><font color="Olive">d</font> <a href="hidden.html#R1">=</a> <font color="Maroon">a</font> ) )
 
<b>by </b><i/>;<br/>
<a NAME="E3:33_2"/><b>then </b>
<font color="Maroon">c</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <font color="Olive">x</font> where <font color="Olive">x</font> is   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font> : ( <font color="Olive">x</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; <font color="Olive">x</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">a</font> ) </span>}</span> 
 
;<br/>
<a NAME="E4:33_2"/><b>then </b>
(  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="lattices.html#R3">[=</a> <font color="Maroon">a</font> &amp; <font color="Maroon">c</font> <a href="lattices.html#R3">[=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> )
 
<b>by </b><i>, <a class="ref" href="lattice3.html#T38">LATTICE3:38</a></i>;<br/>
<b>hence </b><a NAME="E5:33_2"/>
<font color="Maroon">c</font> <a href="hidden.html#R1">=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font>
 <b>by </b><i>, , </i>;<br/>


</div><b>end;</b></div>
<b>hence </b><a NAME="E6:33"/>
(  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> <a href="lattice6.html#NR2" target="_self">is-lower-neighbour-of</a> <font color="Maroon">a</font> &amp; ( for <font color="Olive">c</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>  st <font color="Olive">c</font> <a href="lattice6.html#NR2" target="_self">is-lower-neighbour-of</a> <font color="Maroon">a</font> holds <br/><font color="Olive">c</font> <a href="hidden.html#R1">=</a>  <a href="lattice6.html#K4" target="_self">*'</a> <font color="Maroon">a</font> ) )
 <b>by </b><i>, <a class="txt" href="lattice6.html#E2:33"><i><font color="Green">E24</font></i></a>, <a class="txt" href="lattice6.html#E1"><i><font color="Green">Lemma25</font></i></a>, </i>;<br/>


</div>
