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

<b>let </b><font color="Maroon" title="c1">Y</font> be  non <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>  <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ;<br/><b>let </b><font color="Maroon" title="c2">a</font>, <font color="Maroon" title="c3">b</font>, <font color="Maroon" title="c4">c</font> be    <a href="fraenkel.html#M2" title="FRAENKEL:mode.2">Element</a> of  <a href="fraenkel.html#K1" title="FRAENKEL:func.1">Funcs</a> <font color="Maroon" title="c1">Y</font>,<a href="margrel1.html#K6" title="MARGREL1:func.6">BOOLEAN</a> ;<br/>







<i><font color="Green" title="E12">A1</font></i>: <font color="Maroon" title="c2">a</font> <a href="bvfunc26.html#K3" title="BVFUNC26:func.3">'nand'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc26.html#K4" title="BVFUNC26:func.4">'nor'</a> <font color="Maroon" title="c4">c</font></span>)</span> = 
 <a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">a</font> <a href="margrel1.html#K16" title="MARGREL1:func.16">'&amp;'</a> <span class="p2">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc26.html#K4" title="BVFUNC26:func.4">'nor'</a> <font color="Maroon" title="c4">c</font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc26.html#T1" target="_self" title="BVFUNC26:th.1">Th1</a></i>
<br/>.= 
 <a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">a</font> <a href="margrel1.html#K16" title="MARGREL1:func.16">'&amp;'</a> <span class="p2">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <span class="p3">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc26.html#T2" target="_self" title="BVFUNC26:th.2">Th2</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <font color="Maroon" title="c2">a</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <span class="p1">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <span class="p2">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <span class="p3">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_1.html#T17" title="BVFUNC_1:th.17">BVFUNC_1:17</a></i>
<br/>.= 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <font color="Maroon" title="c2">a</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c3">b</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font>
<b>by </b><i><a class="ref" href="bvfunc_1.html#T11" title="BVFUNC_1:th.11">BVFUNC_1:11</a></i>
;<br/>
<a NAME="E2:18"/><b>then </b>
<font color="Maroon" title="c2">a</font> <a href="bvfunc26.html#K3" title="BVFUNC26:func.3">'nand'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc26.html#K4" title="BVFUNC26:func.4">'nor'</a> <font color="Maroon" title="c4">c</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <font color="Maroon" title="c2">a</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font></span>)</span>
 
<b>by </b><i><a class="ref" href="bvfunc_1.html#T11" title="BVFUNC_1:th.11">BVFUNC_1:11</a></i>;<br/>
<b>hence </b><a NAME="E3:18"/>
( <font color="Maroon" title="c2">a</font> <a href="bvfunc26.html#K3" title="BVFUNC26:func.3">'nand'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc26.html#K4" title="BVFUNC26:func.4">'nor'</a> <font color="Maroon" title="c4">c</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="margrel1.html#K15" title="MARGREL1:func.15">'not'</a> <font color="Maroon" title="c2">a</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c3">b</font></span>)</span> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font> &amp; <font color="Maroon" title="c2">a</font> <a href="bvfunc26.html#K3" title="BVFUNC26:func.3">'nand'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc26.html#K4" title="BVFUNC26:func.4">'nor'</a> <font color="Maroon" title="c4">c</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">a</font> <a href="bvfunc_1.html#K12" title="BVFUNC_1:func.12">'imp'</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">b</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <font color="Maroon" title="c4">c</font></span>)</span> )
 <b>by </b><i><a class="txt" href="bvfunc26.html#E1:18"><i><font color="Green" title="E12">A1</font></i></a>, <a class="ref" href="bvfunc_4.html#T8" title="BVFUNC_4:th.8">BVFUNC_4:8</a></i>;<br/>


</div>
