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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>thus </b><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="bvfunc_1.html#K15">'eqv'</a> <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="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="bvfunc_1.html#K9">'xor'</a> <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></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc25.html#T12">BVFUNC25:12</a></i>
<br/>.= 
 <a href="valuat_1.html#K5">'not'</a> <span class="p1">(<span class="default"><a href="valuat_1.html#K5">'not'</a> <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></span>)</span>
<b>by </b><i><a class="ref" href="bvfunc_8.html#T14">BVFUNC_8:14</a></i>
<br/>.= 
 <a href="bvfunc_1.html#K19">I_el</a> <font color="Maroon">c<sub>1</sub></font>
<b>by </b><i><a class="ref" href="bvfunc_1.html#T4">BVFUNC_1:4</a></i>
;<br/>


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