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<span class="kw">set </span><font color="Maroon" title="c2">L</font> =  <a href="fomodel1.html#K16" title="FOMODEL1:func.16">LettersOf</a> <font color="Maroon" title="c1">S</font>;<br/>
<span class="kw">set </span><font color="Maroon" title="c3">P</font> =  <a href="fomodel1.html#K3" title="FOMODEL1:func.3">OpSymbolsOf</a> <font color="Maroon" title="c1">S</font>;<br/>
<span class="kw">let </span><font color="Maroon" title="c4">s</font> be   <a href="fomodel1.html#NM1" title="FOMODEL1:NM.1">Element</a> of <font color="Maroon" title="c1">S</font>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> ( <font color="Maroon" title="c4">s</font> is  <a href="fomodel1.html#V4" title="FOMODEL1:attr.4">literal</a>  implies  not <font color="Maroon" title="c4">s</font> is  <a href="fomodel1.html#V6" title="FOMODEL1:attr.6">operational</a>  )</span><br/>

<span class="kw">assume </span><a NAME="E1:27_11_1"/><span class="lab"><font color="Green" title="E15">B0</font></span>: 
<font color="Maroon" title="c4">s</font> is  <a href="fomodel1.html#V4" title="FOMODEL1:attr.4">literal</a> 
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide">  not <font color="Maroon" title="c4">s</font> is  <a href="fomodel1.html#V6" title="FOMODEL1:attr.6">operational</a> </span><br/>

<span class="kw">assume </span><a NAME="E2:27_11_1"/>
<font color="Maroon" title="c4">s</font> is  <a href="fomodel1.html#V6" title="FOMODEL1:attr.6">operational</a> 
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> contradiction</span><br/>

<a NAME="E3:27_11_1"/><span class="kw">then </span>
( <font color="Maroon" title="c4">s</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fomodel1.html#K16" title="FOMODEL1:func.16">LettersOf</a> <font color="Maroon" title="c1">S</font> &amp; <font color="Maroon" title="c4">s</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="fomodel1.html#K3" title="FOMODEL1:func.3">OpSymbolsOf</a> <font color="Maroon" title="c1">S</font> )
 
<span class="kw">by</span> <span class="lab"><a class="txt" href="#E1:27_11_1"><span class="lab"><font color="Green" title="E15">B0</font></span></a>, <a class="ref" href="fomodel1.html#D14" target="_self" title="FOMODEL1:def.14">DefLiteral</a>, <a class="ref" href="fomodel1.html#D16" target="_self" title="FOMODEL1:def.16">DefOperational</a></span>;<br/>
<a NAME="E4:27_11_1"/><span class="kw">then </span>
<font color="Maroon" title="c4">s</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1">(<span class="default"><a href="fomodel1.html#K16" title="FOMODEL1:func.16">LettersOf</a> <font color="Maroon" title="c1">S</font></span>)</span> <a href="subset_1.html#K8" title="SUBSET_1:func.8">/\</a> <span class="p1">(<span class="default"><a href="fomodel1.html#K3" title="FOMODEL1:func.3">OpSymbolsOf</a> <font color="Maroon" title="c1">S</font></span>)</span>
 
<span class="kw">by</span> <span class="lab"><a class="ref" href="xboole_0.html#D4" title="XBOOLE_0:def.4">XBOOLE_0:def 4</a></span>;<br/>
<span class="kw">hence </span><a NAME="E5:27_11_1"/>
contradiction
 <span class="kw">by</span> <span class="lab"><a class="ref" href="fomodel1.html#T1" target="_self" title="FOMODEL1:th.1">Lm8</a></span>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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