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<b>let </b><font color="Maroon">G</font> be  non <a href="struct_0.html#V3">empty</a>  <a href="lang1.html#L2" target="_self">GrammarStr</a> ;<br/><b>let </b><font color="Maroon">n</font> be   <a href="lang1.html#NM2">String</a> of <font color="Maroon">G</font>;<br/>



<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="23_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:23_1"/>
<font color="Maroon">n</font> <a href="hidden.html#R2">in</a>  <a href="lang1.html#K7" target="_self">Lang</a> <font color="Maroon">G</font>
 ;<br/><a NAME="E2:23_1"/><b>then </b>
 ex <font color="Olive">a</font> being   <a href="finseq_2.html#M2">Element</a> of the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">G</font> <a href="finseq_2.html#K3">*</a>  st <br/>( <font color="Maroon">n</font> <a href="hidden.html#R1">=</a> <font color="Olive">a</font> &amp;  <a href="relset_1.html#K5">rng</a> <font color="Olive">a</font> <a href="tarski.html#R1">c=</a>  <a href="lang1.html#K5" target="_self">Terminals</a> <font color="Maroon">G</font> &amp; <font color="Olive">a</font> <a href="lang1.html#R3" target="_self">is_derivable_from</a> <span class="p1"><a href="lang1.html#K3" target="_self">&lt;*</a><span class="default">the <a href="lang1.html#U2" target="_self">InitialSym</a> of <font color="Maroon">G</font></span><a href="lang1.html#K3" target="_self">*&gt;</a></span> )
 ;<br/><b>hence </b><a NAME="E3:23_1"/>
(  <a href="relset_1.html#K5">rng</a> <font color="Maroon">n</font> <a href="tarski.html#R1">c=</a>  <a href="lang1.html#K5" target="_self">Terminals</a> <font color="Maroon">G</font> &amp; <font color="Maroon">n</font> <a href="lang1.html#R3" target="_self">is_derivable_from</a> <span class="p1"><a href="lang1.html#K3" target="_self">&lt;*</a><span class="default">the <a href="lang1.html#U2" target="_self">InitialSym</a> of <font color="Maroon">G</font></span><a href="lang1.html#K3" target="_self">*&gt;</a></span> )
 ;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E2:23"/>
( <font color="Maroon">n</font> <a href="hidden.html#R2">in</a>  <a href="lang1.html#K7" target="_self">Lang</a> <font color="Maroon">G</font> iff (  <a href="relset_1.html#K5">rng</a> <font color="Maroon">n</font> <a href="tarski.html#R1">c=</a>  <a href="lang1.html#K5" target="_self">Terminals</a> <font color="Maroon">G</font> &amp; <font color="Maroon">n</font> <a href="lang1.html#R3" target="_self">is_derivable_from</a> <span class="p1"><a href="lang1.html#K3" target="_self">&lt;*</a><span class="default">the <a href="lang1.html#U2" target="_self">InitialSym</a> of <font color="Maroon">G</font></span><a href="lang1.html#K3" target="_self">*&gt;</a></span> ) )
 ;<br/>


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