Editing Context-sensitive grammar (section)

=== ''a<sup>n</sup>b<sup>n</sup>c<sup>n</sup>d<sup>n</sup>'', etc. ===
More complicated grammars can be used to parse { ''a<sup>n</sup>b<sup>n</sup>c<sup>n</sup>d<sup>n</sup>'' | ''n'' ≥ 1 }, and other languages with even more letters. Here we show a simpler approach using non-contracting grammars:{{cn|date=January 2022}}
Start with a kernel of regular productions generating the sentential forms
<math>(ABCD)^{n}abcd</math> and then include the non contracting productions
<math>p_{Da} : Da\rightarrow aD</math>,
<math>p_{Db} : Db\rightarrow bD</math>,
<math>p_{Dc} : Dc\rightarrow cD</math>,
<math>p_{Dd} : Dd\rightarrow dd</math>,
<math>p_{Ca} : Ca\rightarrow aC</math>,
<math>p_{Cb} : Cb\rightarrow bC</math>,
<math>p_{Cc} : Cc\rightarrow cc</math>,
<math>p_{Ba} : Ba\rightarrow aB</math>,
<math>p_{Bb} : Bb\rightarrow bb</math>,
<math>p_{Aa} : Aa\rightarrow aa</math>.