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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  non <a href="struct_0.html#V3">empty</a> <a href="yellow_0.html#V1">lower-bounded</a>  <a href="orders_2.html#L1">RelStr</a> ;<br/>

<b>assume </b><a NAME="E1:134"/><i><font color="Green">E80</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="waybel_1.html#NR13" target="_self">is_a_Heyting_algebra</a> 
 ;<br/>

<a NAME="E2:134"/><b>then </b><i><font color="Green">E81</font></i>: 
<font color="Maroon">c<sub>1</sub></font> is   <a href="waybel_0.html#NM8">LATTICE</a>
 
<b>by </b><i><a class="ref" href="waybel_1.html#D19" target="_self">Def19</a></i>;<br/>
<b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>

<div><b>hereby </b>
<div class="add"><a NAME="E1:134_1"/><i><font color="Green">E82</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <font color="Maroon">c<sub>3</sub></font> <a href="orders_2.html#NR2" target="_self">&gt;=</a>  <a href="yellow_0.html#K3">Bottom</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="waybel_1.html#E2:134"><i><font color="Green">E81</font></i></a>, <a class="ref" href="yellow_0.html#T44">YELLOW_0:44</a></i>;<br/><b>assume </b><a NAME="E2:134_1"/>
 <a href="waybel_1.html#K7" target="_self">'not'</a> <font color="Maroon">c<sub>2</sub></font> <a href="orders_2.html#NR2" target="_self">&gt;=</a> <font color="Maroon">c<sub>3</sub></font>
 ;<br/><a NAME="E3:134_1"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <font color="Maroon">c<sub>3</sub></font> <a href="orders_2.html#R1">&lt;=</a>  <a href="yellow_0.html#K3">Bottom</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="waybel_1.html#E1:134"><i><font color="Green">E80</font></i></a>, <a class="ref" href="waybel_1.html#T70" target="_self">Th70</a></i>;<br/><b>hence </b><a NAME="E4:134_1"/>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="yellow_0.html#K3">Bottom</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="waybel_1.html#E2:134"><i><font color="Green">E81</font></i></a>, <a class="txt" href="waybel_1.html#E1:134_1"><i><font color="Green">E82</font></i></a>, <a class="ref" href="orders_2.html#T25">ORDERS_2:25</a></i>;<br/></div>
<b>end;</b></div>

<b>assume </b><a NAME="E4:134"/>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="yellow_0.html#K3">Bottom</a> <font color="Maroon">c<sub>1</sub></font>
 ;<br/>

<a NAME="E5:134"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <font color="Maroon">c<sub>3</sub></font> <a href="orders_2.html#R1">&lt;=</a>  <a href="yellow_0.html#K3">Bottom</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="txt" href="waybel_1.html#E2:134"><i><font color="Green">E81</font></i></a>, <a class="ref" href="orders_2.html#T24">ORDERS_2:24</a></i>;<br/>
<b>hence </b><a NAME="E6:134"/>
 <a href="waybel_1.html#K7" target="_self">'not'</a> <font color="Maroon">c<sub>2</sub></font> <a href="orders_2.html#NR2" target="_self">&gt;=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="txt" href="waybel_1.html#E1:134"><i><font color="Green">E80</font></i></a>, <a class="ref" href="waybel_1.html#T70" target="_self">Th70</a></i>;<br/>


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