<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">c<sub>1</sub></font> be  <a href="margrel1.html#V2" target="_self">boolean</a>  <a href="hidden.html#M1">set</a> ;<br/>

<div><i><font color="Green">E15</font></i>: <a class="txt" onclick="hs2(this)" href="javascript:()" title="40_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:40_1"/>
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K8" target="_self">TRUE</a> 
 ;<br/><a NAME="E2:40_1"/><b>then </b>
 <a href="margrel1.html#K9" target="_self">'not'</a> <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K7" target="_self">FALSE</a> 
 <b>by </b><i><a class="ref" href="margrel1.html#T41" target="_self">Th41</a></i>;<br/><b>hence </b><a NAME="E3:40_1"/>
<font color="Maroon">c<sub>1</sub></font> <a href="margrel1.html#K10" target="_self">'&amp;'</a> <span class="p1">(<span class="default"><a href="margrel1.html#K9" target="_self">'not'</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K7" target="_self">FALSE</a> 
 <b>by </b><i><a class="ref" href="margrel1.html#T45" target="_self">Th45</a></i>;<br/></div><b>end;</b></div>
<a NAME="E2:40"/>
( <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K7" target="_self">FALSE</a>  implies <font color="Maroon">c<sub>1</sub></font> <a href="margrel1.html#K10" target="_self">'&amp;'</a> <span class="p1">(<span class="default"><a href="margrel1.html#K9" target="_self">'not'</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K7" target="_self">FALSE</a>  )
 
<b>by </b><i><a class="ref" href="margrel1.html#T45" target="_self">Th45</a></i>;<br/>
<b>hence </b><a NAME="E3:40"/>
<font color="Maroon">c<sub>1</sub></font> <a href="margrel1.html#K10" target="_self">'&amp;'</a> <span class="p1">(<span class="default"><a href="margrel1.html#K9" target="_self">'not'</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="margrel1.html#K7" target="_self">FALSE</a> 
 <b>by </b><i><a class="txt" href="margrel1.html#E1:40"><i><font color="Green">E15</font></i></a>, <a class="ref" href="margrel1.html#T39" target="_self">Th39</a></i>;<br/>


</div>
