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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/>



<b>thus </b><a NAME="E1:23"/>
 <a href="zf_lang.html#K20">the_argument_of</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K10">'or'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6">'not'</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="zf_lang.html#K7">'&amp;'</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6">'not'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span>
 <b>by </b><i><a class="ref" href="zf_lang1.html#T3" target="_self">Th3</a></i>;<br/>

<a NAME="E2:23"/>
<font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K10">'or'</a> <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K6">'not'</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="zf_lang.html#K11">=&gt;</a> <font color="Maroon">c<sub>2</sub></font>
 
;<br/>
<b>hence </b><a NAME="E3:23"/>
(  <a href="zf_lang.html#K25">the_antecedent_of</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K10">'or'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a>  <a href="zf_lang.html#K6">'not'</a> <font color="Maroon">c<sub>1</sub></font> &amp;  <a href="zf_lang.html#K26">the_consequent_of</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="zf_lang.html#K10">'or'</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>2</sub></font> )
 <b>by </b><i><a class="ref" href="zf_lang1.html#T6" target="_self">Th6</a></i>;<br/>


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