Commutation-Augmented Pregroup Grammars and Mildly Context-Sensitive Languages
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The paper presents a generalization of pregroup, by which a freely-generated pregroup is augmented with a finite set of commuting inequations, allowing limited commutativity and cancelability. It is shown that grammars based on the commutation-augmented pregroups generate mildly context-sensitive languages. A version of Lambek’s switching lemma is established for these pregroups. Polynomial parsability and semilinearity are shown for languages generated by these grammars.
KeywordsFormal language theory pregroup grammars mildly context-sensitive languages
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