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<b>let </b><font color="Maroon" title="c1">p</font>, <font color="Maroon" title="c2">q</font> be   <a href="zf_lang.html#NM2" title="ZF_LANG:NM.2">ZF-formula</a>;<br/>



<a NAME="E1:4"/>
<font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font> is <a href="zf_lang.html#V5" title="ZF_LANG:attr.5">conjunctive</a>
 
<b>by </b><i><a class="ref" href="zf_lang.html#T16" title="ZF_LANG:th.16">ZF_LANG:16</a></i>;<br/>
<a NAME="E2:4"/><b>then </b>
<font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K21" title="ZF_LANG:func.21">the_left_argument_of</a> <span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <span class="p1">(<span class="default"><a href="zf_lang.html#K22" title="ZF_LANG:func.22">the_right_argument_of</a> <span class="p2">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span></span>)</span>
 
<b>by </b><i><a class="ref" href="zf_lang.html#T58" title="ZF_LANG:th.58">ZF_LANG:58</a></i>;<br/>
<b>hence </b><a NAME="E3:4"/>
(  <a href="zf_lang.html#K21" title="ZF_LANG:func.21">the_left_argument_of</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c1">p</font> &amp;  <a href="zf_lang.html#K22" title="ZF_LANG:func.22">the_right_argument_of</a> <span class="p1">(<span class="default"><font color="Maroon" title="c1">p</font> <a href="zf_lang.html#K7" title="ZF_LANG:func.7">'&amp;'</a> <font color="Maroon" title="c2">q</font></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">q</font> )
 <b>by </b><i><a class="ref" href="zf_lang.html#T47" title="ZF_LANG:th.47">ZF_LANG:47</a></i>;<br/>


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