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<b>let </b><font color="Maroon">F</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">G</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">F1</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">G1</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/>







<b>assume </b><a NAME="E1:46"/><i><font color="Green">E31</font></i>: 
<font color="Maroon">F</font> <a href="zf_lang.html#K10" target="_self">'or'</a> <font color="Maroon">G</font> <a href="hidden.html#R1">=</a> <font color="Maroon">F1</font> <a href="zf_lang.html#K10" target="_self">'or'</a> <font color="Maroon">G1</font>
 ;<br/>

<a NAME="E2:46"/>
<span class="p1">(<span class="default"><a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">F</font></span>)</span> <a href="zf_lang.html#K7" target="_self">'&amp;'</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">G</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">F1</font></span>)</span> <a href="zf_lang.html#K7" target="_self">'&amp;'</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">G1</font></span>)</span>
 
<b>by </b><i><a class="ref" href="zf_lang.html#T10" target="_self">Th10</a>, </i>;<br/>
<a NAME="E3:46"/><b>then </b>
(  <a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">F</font> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">F1</font> &amp;  <a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">G</font> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K6" target="_self">'not'</a> <font color="Maroon">G1</font> )
 
<b>by </b><i><a class="txt" href="zf_lang.html#E1:46"><i><font color="Green">E31</font></i></a></i>;<br/>
<b>hence </b><a NAME="E4:46"/>
( <font color="Maroon">F</font> <a href="hidden.html#R1">=</a> <font color="Maroon">F1</font> &amp; <font color="Maroon">G</font> <a href="hidden.html#R1">=</a> <font color="Maroon">G1</font> )
 <b>by </b><i/>;<br/>


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