Topic
Chomsky hierarchy
About: Chomsky hierarchy is a research topic. Over the lifetime, 601 publications have been published within this topic receiving 31067 citations. The topic is also known as: Chomsky–Schützenberger hierarchy.
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TL;DR: For non-Abelian free groups with finitely many generators, the following is shown: the level of a language in the Chomsky hierarchy is independent of the automatic representation; the context-free verbal languages are only the full group and the language of the empty word.
TL;DR: The paper focuses on the inference of inflectional rule systems which differs in many aspects from the traditional production rule system of Chomsky grammars, and compares the main candidate methods on the learning of objective-case in the Hungarian language.
TL;DR: It is shown that binary context-free grammars can generate matrix languages whereas binary regular and linear Grammars have the same power as Chomskyan regular andlinear grammar.
Abstract: A binary grammar is a relational grammar with two nonterminal alphabets, two terminal alphabets, a set of pairs of productions and the pair of the initial nonterminals that generates the binary relation, i.e., the set of pairs of strings over the terminal alphabets. This paper investigates the binary context-free grammars as mutually controlled grammars: two context-free grammars generate strings imposing restrictions on selecting production rules to be applied in derivations. The paper shows that binary context-free grammars can generate matrix languages whereas binary regular and linear grammars have the same power as Chomskyan regular and linear grammars.
Journal Article•
TL;DR: In this article, it was shown that the class of enumerable languages is not reflexive, and that the classes of context-free, context-sensitive, and computable languages are reflexive.
Abstract: The class of regular languages can be generated from the regular expressions. These regular expressions, however, do not themselves form a regular language, as can be seen using the pumping lemma. On the other hand, the class of enumerable languages can be enumerated by a universal language that is one of its elements. We say that the enumerable languages are reflexive. In this paper we investigate what other classes of the Chomsky Hierarchy are reflexive in this sense. To make this precise we require that the decoding function is itself specified by a member of the same class. Could it be that the regular languages are reflexive, by using a different collection of codes? It turns out that this is impossible: the collection of regular languages is not reflexive. Similarly the collections of the context-free, context-sensitive, and computable languages are not reflexive. Therefore the class of enumerable languages is the only reflexive one in the Chomsky Hierarchy.