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

<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> 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/>



<a NAME="E1:7"/>
<span class="p1">(<span class="default"><a href="bvfunc_1.html#K19">I_el</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="bvfunc26.html#K3" target="_self">'nand'</a> <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R1">=</a>  <a href="valuat_1.html#K5">'not'</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="bvfunc_1.html#K19">I_el</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="valuat_1.html#K6">'&amp;'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="bvfunc26.html#T1" target="_self">Th1</a></i>;<br/>
<b>hence </b><a NAME="E2:7"/>
<span class="p1">(<span class="default"><a href="bvfunc_1.html#K19">I_el</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="bvfunc26.html#K3" target="_self">'nand'</a> <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R1">=</a>  <a href="valuat_1.html#K5">'not'</a> <font color="Maroon">c<sub>2</sub></font>
 <b>by </b><i><a class="ref" href="bvfunc_1.html#T9">BVFUNC_1:9</a></i>;<br/>


</div>
