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<b>let </b><font color="Maroon">L</font> be  non <a href="struct_0.html#V3">empty</a> <a href="waybel_1.html#V11">Boolean</a>  <a href="orders_2.html#L1">RelStr</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>let </b><font color="Maroon">b</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/><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>let </b><font color="Maroon">d</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>









<b>assume </b><b>that </b><br/><a NAME="E1:45"/><i><font color="Green">E11</font></i>: 
<font color="Maroon">a</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">b</font>
 <b>and </b><br/><a NAME="E2:45"/><i><font color="Green">E16</font></i>: 
<font color="Maroon">c</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">d</font>
 ;<br/>

<a NAME="E3:45"/>
 <a href="waybel_1.html#K7">'not'</a> <font color="Maroon">d</font> <a href="orders_2.html#R3">&lt;=</a>  <a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font>
 
<b>by </b><i><a class="ref" href="yellow_5.html#T7" target="_self">Th7</a>, <a class="ref" href="yellow_5.html#T6" target="_self">Th6</a></i>;<br/>
<a NAME="E4:45"/><b>then </b><i><font color="Green">E24</font></i>: 
<font color="Maroon">a</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">d</font></span>)</span> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">a</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font></span>)</span>
 
<b>by </b><i/>;<br/>
<a NAME="E5:45"/>
<font color="Maroon">a</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font></span>)</span> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">b</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font></span>)</span>
 
<b>by </b><i><a class="txt" href="yellow_5.html#E2:45"><i><font color="Green">E16</font></i></a>, </i>;<br/>
<a NAME="E6:45"/><b>then </b>
<font color="Maroon">a</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">d</font></span>)</span> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">b</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font></span>)</span>
 
<b>by </b><i><a class="ref" href="yellow_5.html#T8" target="_self">Th8</a>, <a class="ref" href="yellow_0.html#D2">YELLOW_0:def 2</a></i>;<br/>
<a NAME="E7:45"/><b>then </b>
<font color="Maroon">a</font> <a href="yellow_5.html#K1" target="_self">\</a> <font color="Maroon">d</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">b</font> <a href="lattice3.html#K12">"/\"</a> <span class="p1">(<span class="default"><a href="waybel_1.html#K7">'not'</a> <font color="Maroon">c</font></span>)</span>
 
;<br/>
<b>hence </b><a NAME="E8:45"/>
<font color="Maroon">a</font> <a href="yellow_5.html#K1" target="_self">\</a> <font color="Maroon">d</font> <a href="orders_2.html#R3">&lt;=</a> <font color="Maroon">b</font> <a href="yellow_5.html#K1" target="_self">\</a> <font color="Maroon">c</font>
 ;<br/>


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