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

<b>let </b><font color="Maroon">L</font> be  <a href="yellow_0.html#V1">lower-bounded</a> <a href="waybel_8.html#V2">algebraic</a> <a href="waybel_0.html#NM7">sup-Semilattice</a>;<br/><b>let </b><font color="Maroon">x</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>



<b>thus </b><a NAME="E1:18"/>
(  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is  <a href="waybel_0.html#V14">principal</a> <a href="waybel_0.html#NM3">Ideal</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> implies <font color="Maroon">x</font> is <a href="waybel_3.html#V1">compact</a> )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="18_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:18_1"/>
 <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is  <a href="waybel_0.html#V14">principal</a> <a href="waybel_0.html#NM3">Ideal</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span>
 ;<br/>

<b>then consider </b><font color="Maroon">y</font> being   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span><b> such that </b><br/><a NAME="E3:18_1"/><i><font color="Green">E30</font></i>: 
<font color="Maroon">y</font> <a href="hidden.html#R2">in</a>  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font>
 <b>and </b><br/><a NAME="E4:18_1"/><i><font color="Green">E34</font></i>: 
<font color="Maroon">y</font> <a href="lattice3.html#NR4" target="_self">is_&gt;=_than</a>  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font>
 <b>by </b><i><a class="ref" href="waybel_0.html#D21">WAYBEL_0:def 21</a></i>;<br/>
<b>reconsider </b><font color="Maroon">y'</font> = <font color="Maroon">y</font> as   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font> <b>by </b><i><a class="ref" href="yellow_0.html#T59">YELLOW_0:59</a></i>;<br/>
<a NAME="E6:18_1"/>
 <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span>
 
<b>by </b><i/>;<br/>
<a NAME="E7:18_1"/><b>then </b>
<font color="Maroon">y'</font> <a href="lattice3.html#NR4" target="_self">is_&gt;=_than</a>  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font>
 
<b>by </b><i>, <a class="ref" href="yellow_0.html#T63">YELLOW_0:63</a></i>;<br/>
<a NAME="E8:18_1"/><b>then </b>
<font color="Maroon">y'</font> <a href="orders_2.html#NR2" target="_self">&gt;=</a>  <a href="yellow_0.html#NK3" target="_self">sup</a> <span class="p1">(<span class="default"><a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font></span>)</span>
 
<b>by </b><i><a class="ref" href="yellow_0.html#T32">YELLOW_0:32</a></i>;<br/>
<a NAME="E9:18_1"/><b>then </b><i><font color="Green">E35</font></i>: 
<font color="Maroon">x</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">y'</font>
 
<b>by </b><i><a class="ref" href="waybel_8.html#D3">WAYBEL_8:def 3</a></i>;<br/>
<a NAME="E10:18_1"/>
( <font color="Maroon">y'</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">x</font> &amp; <font color="Maroon">y'</font> is <a href="waybel_3.html#V1">compact</a> )
 
<b>by </b><i>, <a class="ref" href="waybel_8.html#T4">WAYBEL_8:4</a></i>;<br/>
<b>hence </b><a NAME="E11:18_1"/>
<font color="Maroon">x</font> is <a href="waybel_3.html#V1">compact</a>
 <b>by </b><i>, <a class="ref" href="orders_2.html#T25">ORDERS_2:25</a></i>;<br/>


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

<b>thus </b><a NAME="E2:18"/>
( <font color="Maroon">x</font> is <a href="waybel_3.html#V1">compact</a> implies  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is  <a href="waybel_0.html#V14">principal</a> <a href="waybel_0.html#NM3">Ideal</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="18_2"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:18_2"/><i><font color="Green">E36</font></i>: 
<font color="Maroon">x</font> is <a href="waybel_3.html#V1">compact</a>
 ;<br/>

<a NAME="E2:18_2"/><i><font color="Green">E49</font></i>: 
 <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is  non <a href="xboole_0.html#V1">empty</a> <a href="waybel_0.html#V1">directed</a> <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">L</font>
 
<b>by </b><i><a class="ref" href="waybel_8.html#D4">WAYBEL_8:def 4</a></i>;<br/>
<b>reconsider </b><font color="Maroon">I</font> =  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> as  non <a href="xboole_0.html#V1">empty</a> <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> <b>by </b><i/>;<br/>
<b>reconsider </b><font color="Maroon">I</font> = <font color="Maroon">I</font> as  non <a href="xboole_0.html#V1">empty</a> <a href="waybel_0.html#V1">directed</a> <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> <b>by </b><i>, <a class="ref" href="waybel10.html#T24">WAYBEL10:24</a></i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="18_2_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">y</font> be   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span>, <font color="Maroon">z</font> be   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span>;<br/><b>reconsider </b><font color="Maroon">y'</font> = <font color="Maroon">y</font>, <font color="Maroon">z'</font> = <font color="Maroon">z</font> as   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font> <b>by </b><i><a class="ref" href="yellow_0.html#T59">YELLOW_0:59</a></i>;<br/><b>assume </b><a NAME="E2:18_2_1"/><i><font color="Green">E50</font></i>: 
( <font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">I</font> &amp; <font color="Maroon">z</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">y</font> )
 ;<br/><a NAME="E3:18_2_1"/><b>then </b><i><font color="Green">E56</font></i>: 
<font color="Maroon">y'</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">x</font>
 <b>by </b><i><a class="ref" href="waybel_8.html#T4">WAYBEL_8:4</a></i>;<br/><a NAME="E4:18_2_1"/>
<font color="Maroon">z'</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">y'</font>
 <b>by </b><i>, <a class="ref" href="yellow_0.html#T60">YELLOW_0:60</a></i>;<br/><a NAME="E5:18_2_1"/><b>then </b><i><font color="Green">E57</font></i>: 
<font color="Maroon">z'</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">x</font>
 <b>by </b><i>, <a class="ref" href="orders_2.html#T26">ORDERS_2:26</a></i>;<br/><a NAME="E6:18_2_1"/>
<font color="Maroon">z'</font> is <a href="waybel_3.html#V1">compact</a>
 <b>by </b><i><a class="ref" href="waybel_8.html#D1">WAYBEL_8:def 1</a></i>;<br/><b>hence </b><a NAME="E7:18_2_1"/>
<font color="Maroon">z</font> <a href="hidden.html#R2">in</a> <font color="Maroon">I</font>
 <b>by </b><i>, <a class="ref" href="waybel_8.html#T4">WAYBEL_8:4</a></i>;<br/></div><b>end;</b></div>
<b>then reconsider </b><font color="Maroon">I</font> = <font color="Maroon">I</font> as   <a href="waybel_0.html#NM3">Ideal</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> <b>by </b><i><a class="ref" href="waybel_0.html#D19">WAYBEL_0:def 19</a></i>;<br/>
<b>reconsider </b><font color="Maroon">x'</font> = <font color="Maroon">x</font> as   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span> <b>by </b><i>, <a class="ref" href="waybel_8.html#D1">WAYBEL_8:def 1</a></i>;<br/>
<a NAME="E8:18_2"/>
<font color="Maroon">x</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">x</font>
 
;<br/>
<a NAME="E9:18_2"/><b>then </b><i><font color="Green">E58</font></i>: 
<font color="Maroon">x'</font> <a href="hidden.html#R2">in</a> <font color="Maroon">I</font>
 
<b>by </b><i>, <a class="ref" href="waybel_8.html#T4">WAYBEL_8:4</a></i>;<br/>
<a NAME="E10:18_2"/>
 <a href="yellow_0.html#NK3" target="_self">sup</a> <span class="p1">(<span class="default"><a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font></span>)</span> <a href="lattice3.html#NR4" target="_self">is_&gt;=_than</a>  <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font>
 
<b>by </b><i><a class="ref" href="yellow_0.html#T32">YELLOW_0:32</a></i>;<br/>
<a NAME="E11:18_2"/><b>then </b>
<font color="Maroon">x</font> <a href="lattice3.html#NR4" target="_self">is_&gt;=_than</a> <font color="Maroon">I</font>
 
<b>by </b><i><a class="ref" href="waybel_8.html#D3">WAYBEL_8:def 3</a></i>;<br/>
<a NAME="E12:18_2"/><b>then </b>
<font color="Maroon">x'</font> <a href="lattice3.html#NR4" target="_self">is_&gt;=_than</a> <font color="Maroon">I</font>
 
<b>by </b><i><a class="ref" href="yellow_0.html#T62">YELLOW_0:62</a></i>;<br/>
<b>hence </b><a NAME="E13:18_2"/>
 <a href="waybel_8.html#K2">compactbelow</a> <font color="Maroon">x</font> is  <a href="waybel_0.html#V14">principal</a> <a href="waybel_0.html#NM3">Ideal</a> of <span class="p1">(<span class="default"><a href="waybel_8.html#K1">CompactSublatt</a> <font color="Maroon">L</font></span>)</span>
 <b>by </b><i>, <a class="ref" href="waybel_0.html#D21">WAYBEL_0:def 21</a></i>;<br/>


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


</div>
