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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</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="fraenkel.html#M2">Element</a> of  <a href="fraenkel.html#K1">Funcs</a> <font color="Maroon">c<sub>1</sub></font>,<a href="margrel1.html#K6">BOOLEAN</a> ;<br/>







<b>thus </b><font color="Maroon">c<sub>2</sub></font> <a href="bvfunc_1.html#K14">'imp'</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="bvfunc26.html#K4" target="_self">'nor'</a> <font color="Maroon">c<sub>4</sub></font></span>)</span> = 
<font color="Maroon">c<sub>2</sub></font> <a href="bvfunc_1.html#K14">'imp'</a> <span class="p1">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="bvfunc_1.html#K8">'or'</a> <font color="Maroon">c<sub>4</sub></font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc26.html#T2" target="_self">Th2</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="bvfunc_1.html#K8">'or'</a> <span class="p1">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="bvfunc_1.html#K8">'or'</a> <font color="Maroon">c<sub>4</sub></font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_4.html#T8">BVFUNC_4:8</a></i>
<br/>.= 
 <a href="valuat_1.html#K5">'not'</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="valuat_1.html#K6">'&amp;'</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="bvfunc_1.html#K8">'or'</a> <font color="Maroon">c<sub>4</sub></font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_1.html#T17">BVFUNC_1:17</a></i>
;<br/>


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