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<b>let </b><font color="Maroon">Y</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">a</font> be    <a href="fraenkel.html#M2">Element</a> of  <a href="fraenkel.html#K1">Funcs</a> <font color="Maroon">Y</font>,<a href="margrel1.html#K6">BOOLEAN</a> ;<br/><b>let </b><font color="Maroon">b</font> be    <a href="fraenkel.html#M2">Element</a> of  <a href="fraenkel.html#K1">Funcs</a> <font color="Maroon">Y</font>,<a href="margrel1.html#K6">BOOLEAN</a> ;<br/>





<a NAME="E1:16"/>
<font color="Maroon">a</font> <a href="bvfunc_1.html#K7">'xor'</a> <font color="Maroon">b</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">a</font></span>)</span> <a href="valuat_1.html#K6">'&amp;'</a> <font color="Maroon">b</font></span>)</span> <a href="bvfunc_1.html#K6">'or'</a> <span class="p1">(<span class="default"><font color="Maroon">a</font> <a href="valuat_1.html#K6">'&amp;'</a> <span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">b</font></span>)</span></span>)</span>
 
<b>by </b><i><a class="ref" href="bvfunc_4.html#T9">BVFUNC_4:9</a></i>;<br/>
<b>hence </b><a NAME="E2:16"/>
<span class="p1">(<span class="default"><font color="Maroon">a</font> <a href="bvfunc_1.html#K6">'or'</a> <font color="Maroon">b</font></span>)</span> <a href="valuat_1.html#K6">'&amp;'</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">a</font></span>)</span> <a href="bvfunc_1.html#K6">'or'</a> <span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">b</font></span>)</span></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">a</font></span>)</span> <a href="valuat_1.html#K6">'&amp;'</a> <font color="Maroon">b</font></span>)</span> <a href="bvfunc_1.html#K6">'or'</a> <span class="p1">(<span class="default"><font color="Maroon">a</font> <a href="valuat_1.html#K6">'&amp;'</a> <span class="p2">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <font color="Maroon">b</font></span>)</span></span>)</span>
 <b>by </b><i><a class="ref" href="bvfunc_8.html#T13">BVFUNC_8:13</a></i>;<br/>


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