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<b>let </b><font color="Maroon">A</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">u</font> be   <a href="struct_0.html#NM1">Element</a> of <span class="p1">(<span class="default"><a href="normform.html#K12">NormForm</a> <font color="Maroon">A</font></span>)</span>;<br/>



<b>reconsider </b><font color="Maroon">zero</font> =  <a href="xboole_0.html#K1">{}</a>  as    <a href="subset_1.html#M2">Element</a> of  <a href="normform.html#K8">Normal_forms_on</a> <font color="Maroon">A</font> <b>by </b><i><a class="ref" href="normform.html#T51">NORMFORM:51</a></i>;<br/>
<a NAME="E2:40"/><i><font color="Green">E21</font></i>: 
 <a href="heyting1.html#K3" target="_self">@</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="heyting1.html#K8" target="_self">pseudo_compl</a> <font color="Maroon">A</font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">u</font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="normform.html#K9">mi</a> <span class="p1">(<span class="default"><a href="heyting1.html#K6" target="_self">-</a> <span class="p2">(<span class="default"><a href="heyting1.html#K3" target="_self">@</a> <font color="Maroon">u</font></span>)</span></span>)</span>
 
<b>by </b><i/>;<br/>
<b>thus </b><font color="Maroon">u</font> <a href="lattices.html#K4">"/\"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="heyting1.html#K8" target="_self">pseudo_compl</a> <font color="Maroon">A</font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">u</font></span>)</span> = 
<font color="Maroon">H<sub>2</sub></font>(<font color="Maroon">A</font>) <a href="binop_1.html#K2">.</a> <font color="Maroon">u</font>,<span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="heyting1.html#K8" target="_self">pseudo_compl</a> <font color="Maroon">A</font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">u</font></span>)</span>
<b>by </b><i><a class="ref" href="lattices.html#D2">LATTICES:def 2</a></i>
<br/>.= 
 <a href="normform.html#K9">mi</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="heyting1.html#K3" target="_self">@</a> <font color="Maroon">u</font></span>)</span> <a href="normform.html#K10">^</a> <span class="p2">(<span class="default"><a href="normform.html#K9">mi</a> <span class="p3">(<span class="default"><a href="heyting1.html#K6" target="_self">-</a> <span class="p4">(<span class="default"><a href="heyting1.html#K3" target="_self">@</a> <font color="Maroon">u</font></span>)</span></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="heyting1.html#T3" target="_self">Th3</a>, </i>
<br/>.= 
 <a href="normform.html#K9">mi</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="heyting1.html#K3" target="_self">@</a> <font color="Maroon">u</font></span>)</span> <a href="normform.html#K10">^</a> <span class="p2">(<span class="default"><a href="heyting1.html#K6" target="_self">-</a> <span class="p3">(<span class="default"><a href="heyting1.html#K3" target="_self">@</a> <font color="Maroon">u</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="normform.html#T75">NORMFORM:75</a></i>
<br/>.= 
 <a href="normform.html#K9">mi</a> <font color="Maroon">zero</font>
<b>by </b><i/>
<br/>.= 
 <a href="xboole_0.html#K1">{}</a> 
<b>by </b><i/>
<br/>.= 
 <a href="lattices.html#K5">Bottom</a> <span class="p1">(<span class="default"><a href="normform.html#K12">NormForm</a> <font color="Maroon">A</font></span>)</span>
<b>by </b><i><a class="ref" href="normform.html#T86">NORMFORM:86</a></i>
;<br/>


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