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<b>let </b><font color="Maroon">L</font> be  non <a href="struct_0.html#V3">empty</a> <a href="robbins2.html#V1" target="_self">satisfying_DN_1</a>  <a href="robbins1.html#L2">ComplLattStr</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>, <font color="Maroon">y</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">L</font>;<br/>



<font color="Maroon">x</font> <a href="robbins1.html#NK4" target="_self">+</a> <font color="Maroon">y</font> = 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">x</font> <a href="robbins1.html#NK4" target="_self">+</a> <font color="Maroon">y</font></span>)</span> <a href="robbins1.html#K3">`</a> </span>)</span> <a href="robbins1.html#K3">`</a> 
<b>by </b><i><a class="ref" href="robbins2.html#T8" target="_self">Th8</a></i>
<br/>.= 
<font color="Maroon">y</font> <a href="robbins1.html#NK4" target="_self">+</a> <font color="Maroon">x</font>
<b>by </b><i><a class="ref" href="robbins2.html#T10" target="_self">Th10</a></i>
;<br/>
<b>hence </b><a NAME="E2:30"/>
<font color="Maroon">x</font> <a href="robbins1.html#NK4" target="_self">+</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y</font> <a href="robbins1.html#NK4" target="_self">+</a> <font color="Maroon">x</font>
 ;<br/>


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