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The Chomsky hierarchy in the fields of formal language theory, computer science, and linguistics, is a containment hierarchy of classes of formal grammars. A formal grammar describes how to form strings from a language's vocabulary (or alphabet) that are valid according to the language's syntax.
Chomsky (1959) introduced the Chomsky hierarchy, in which context-sensitive grammars occur as "type 1" grammars; general noncontracting grammars do not occur. [2]Chomsky (1963) calls a noncontracting grammar a "type 1 grammar", and a context-sensitive grammar a "type 2 grammar", and by presenting a conversion from the former into the latter, proves the two weakly equivalent.
Writing systems are used to record human language, and may be classified according to certain common features. The usual name of the script is given first; the name of the languages in which the script is written follows (in brackets), particularly in the case where the language name differs from the script name. Other informative or qualifying ...
The most famous work in the Hippocratic Corpus is the Hippocratic Oath, a landmark declaration of medical ethics. The Hippocratic Oath is both philosophical and practical; it not only deals with abstract principles but practical matters such as removing stones and aiding one's teacher financially.
To convert a grammar to Chomsky normal form, a sequence of simple transformations is applied in a certain order; this is described in most textbooks on automata theory. [4]: 87–94 [5] [6] [7] The presentation here follows Hopcroft, Ullman (1979), but is adapted to use the transformation names from Lange, Leiß (2009).
The set of all context-free languages is identical to the set of languages accepted by pushdown automata, which makes these languages amenable to parsing.Further, for a given CFG, there is a direct way to produce a pushdown automaton for the grammar (and thereby the corresponding language), though going the other way (producing a grammar given an automaton) is not as direct.
Morphological typology is a way of classifying the languages of the world that groups languages according to their common morphological structures. The field organizes languages on the basis of how those languages form words by combining morphemes.
The concept of non-configurationality was developed by grammarians working within Noam Chomsky's generative framework. Some of these linguists observed that the Syntactic Universals proposed by Chomsky and which required a rigid phrase structure was challenged by the syntax of some of the world's languages that had a much less rigid syntax than that of the languages on which Chomsky had based ...