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<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/>







<b>thus </b><font color="Maroon" title="c2">a</font> <a href="bvfunc_1.html#K7" title="BVFUNC_1:func.7">'xor'</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> = 
<font color="Maroon" title="c2">a</font> <a href="bvfunc_1.html#K7" title="BVFUNC_1:func.7">'xor'</a> <span class="p1">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'not'</a> <span class="p2">(<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>
<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"><font color="Maroon" title="c2">a</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <span class="p2">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'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> <a href="valuat_1.html#K6" title="VALUAT_1:func.6">'&amp;'</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'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="p2">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'not'</a> <span class="p3">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'not'</a> <span class="p4">(<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></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_8.html#T13" title="BVFUNC_8:th.13">BVFUNC_8:13</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c2">a</font> <a href="bvfunc_1.html#K6" title="BVFUNC_1:func.6">'or'</a> <span class="p2">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'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> <a href="valuat_1.html#K6" title="VALUAT_1:func.6">'&amp;'</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><a href="valuat_1.html#K5" title="VALUAT_1:func.5">'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></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_1.html#T11" title="BVFUNC_1:th.11">BVFUNC_1:11</a></i>
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