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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="lattices.html#NM8">B_Lattice</a>;<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="E1:28"/>
<font color="Maroon">c<sub>2</sub></font> <a href="lattices.html#R3">[=</a> <font color="Maroon">c<sub>3</sub></font>
 ;<br/>

<a NAME="E2:28"/><b>then </b><i><font color="Green">E15</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="lattices.html#K7">`</a>  <a href="lattices.html#R3">[=</a> <font color="Maroon">c<sub>2</sub></font> <a href="lattices.html#K7">`</a> 
 
<b>by </b><i><a class="ref" href="lattices.html#T53">LATTICES:53</a></i>;<br/>
<b>thus </b><a NAME="E3:28"/>
<font color="Maroon">c<sub>4</sub></font> <a href="boolealg.html#K1" target="_self">\</a> <font color="Maroon">c<sub>3</sub></font> <a href="lattices.html#R3">[=</a> <font color="Maroon">c<sub>4</sub></font> <a href="boolealg.html#K1" target="_self">\</a> <font color="Maroon">c<sub>2</sub></font>
 <b>by </b><i><a class="txt" href="boolealg.html#E2:28"><i><font color="Green">E15</font></i></a>, <a class="ref" href="lattices.html#T27">LATTICES:27</a></i>;<br/>


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