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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="orders_2.html#L1">RelStr</a> ;<br/>

<b>assume </b><a NAME="E1:127"/><i><font color="Green">E76</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="E2:127"/><b>then </b><i><font color="Green">E77</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>, <font color="Maroon">c<sub>4</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>

<b>assume </b><a NAME="E3:127"/><i><font color="Green">E78</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="orders_2.html#R1">&lt;=</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<a NAME="E4:127"/>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="waybel_1.html#K6" target="_self">=&gt;</a> <font color="Maroon">c<sub>3</sub></font></span>)</span> <a href="orders_2.html#R1">&lt;=</a> <font color="Maroon">c<sub>3</sub></font>
 
<b>by </b><i><a class="txt" href="waybel_1.html#E1:127"><i><font color="Green">E76</font></i></a>, <a class="txt" href="waybel_1.html#E103"><i><font color="Green">Lemma74</font></i></a></i>;<br/>
<a NAME="E5:127"/><b>then </b>
<font color="Maroon">c<sub>2</sub></font> <a href="lattice3.html#K11">"/\"</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="waybel_1.html#K6" target="_self">=&gt;</a> <font color="Maroon">c<sub>3</sub></font></span>)</span> <a href="orders_2.html#R1">&lt;=</a> <font color="Maroon">c<sub>4</sub></font>
 
<b>by </b><i><a class="txt" href="waybel_1.html#E2:127"><i><font color="Green">E77</font></i></a>, <a class="txt" href="waybel_1.html#E3:127"><i><font color="Green">E78</font></i></a>, <a class="ref" href="orders_2.html#T26">ORDERS_2:26</a></i>;<br/>
<b>hence </b><a NAME="E6:127"/>
<font color="Maroon">c<sub>2</sub></font> <a href="waybel_1.html#K6" target="_self">=&gt;</a> <font color="Maroon">c<sub>3</sub></font> <a href="orders_2.html#R1">&lt;=</a> <font color="Maroon">c<sub>2</sub></font> <a href="waybel_1.html#K6" target="_self">=&gt;</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="waybel_1.html#E1:127"><i><font color="Green">E76</font></i></a>, <a class="ref" href="waybel_1.html#T70" target="_self">Th70</a></i>;<br/>


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