Showing papers on "Chomsky hierarchy published in 1974"

Formal grammars in linguistics and psycholinguistics

Abstract: Almost four decades have passed since Formal Grammars first appeared in 1974. At that time it was still possible to rather comprehensively review for (psycho)linguists the relevant literature on the theory of formal languages and automata, on their applications in linguistic theory and in the psychology of language. That is no longer feasible. In all three areas developments have been substantial, if not breathtaking. Nowadays, an interested linguist or psycholinguist opening any text on formal languages can no longer see the wood for the trees, as it is by no means evident which formal, mathematical tools are really required for natural language applications. An historical perspective can be helpful here. There are paths through the wood that have been beaten since decades; they can still provide useful orientation. The origins of these paths can be traced in the three volumes of Formal Grammars , brought together in the present re-edition. In a newly added postscript the author has sketched what has become, after all these years, of formal grammars in linguistics and psycholinguistics, or at least some of the core developments. This chapter may provide further motivation for the reader to make a trip back to some of the historical sources.

One-sided and two-sided context in formal grammars

Abstract: A proof for the equivalence of context-sensitive and one-sided contextsensitive languages is given. This yields as a corollary the normal form A → BC, AB → AC, A → a for context-sensitive grammars.

Simple Program Schemes and Formal Languages

Abstract: Inevitably, reading is one of the requirements to be undergone. To improve the performance and quality, someone needs to have something new every day. It will suggest you to have more inspirations, then. However, the needs of inspirations will make you searching for some sources. Even from the other people experience, internet, and many books. Books and internet are the recommended media to help you improving your quality and performance.

A Generalisation of Parikh's Theorem in Formal Language Theory

Abstract: We show that when a family of languages F has a few appropriate closure-properties, all languages algebraic over F are still equivalent to languages in F when occurrences of symbols are permuted At the same time, the methods used imply a new and simple algebraic proof of Parikh’s original theorem, directly transforming an arbitrary context-free grammar into a letter-equivalent regular grammar Further applications are discussed

Nonterminals versus homomorphisms in defining languages for some classes of rewriting systems

Abstract: Given a rewriting system G (its alphabet, the set of productions and the axiom) one can define the language of G by The "trade-offs" between these two mechanisms for defining languages are discussed for both "parallel" rewriting systems from the developmental systems hierarchy and "sequential" rewriting systems from the Chomsky hierarchy.

Adult Languages of L Systems and the Chomsky Hierarchy

Abstract: Theorems 1 – 4 give us a satisfactory analysis of L systems from the point of view of the adult languages they generate, for they establish direct correspondences with three of the four main classes of languages in the Chomsky hierarchy. The remaining class is that of the regular languages, and it is an easy exercise to restrict the form of the productions of a 0L system to ensure that its adult language is regular. In Walker† it is shown that the result for 2L systems can be extended to 〈k, l〉L systems (see Herman and Rozenberg [45] for the definition of such systems) with k+l≥1, and that the result for P2L systems can be extended to P L systems with k, l≥1.

Some Grammars and Recognizers for Formal and Natural Languages

Abstract: Language as an instrument of communication and carrier of information is a very complex phenomenon. It is a psychophysical entity, because the performance of a language is surely as much dependent on its physical environment as on the mental nuances of its users. Historical factors, emotions, and all other elements which constitute the complex structure and workings of the human mind and human institutions have significant roles in the usage and development of languages.

Codes Over Languages

Abstract: This correspondence discusses a restrictive structure of the customary hierarchy of formal languages attained by imposing restrictions on a set of productions and on their Iuse by means of codewords. A coded fuzzy language (CFL) is defined in order gap between formal languages and natural languages. Somte properties of CFLs and their relationships to the restrictive device are studied. A cyclic language of order n is defined to investigate properties of formal and fuzzy languages with regard to classes of recognizers.

Formal grammars in linguistics and psycholinguistics: Vol. I, An introduction to the theory of formal languages and automata

Abstract: The present text is a re-edition of Volume I of Formal Grammars in Linguistics and Psycholinguistics , a three-volume work published in 1974. This volume is an entirely self-contained introduction to the theory of formal grammars and automata, which hasn’t lost any of its relevance. Of course, major new developments have seen the light since this introduction was first published, but it still provides the indispensible basic notions from which later work proceeded. The author’s reasons for writing this text are still relevant: an introduction that does not suppose an acquaintance with sophisticated mathematical theories and methods, that is intended specifically for linguists and psycholinguists (thus including such topics as learnability and probabilistic grammars), and that provides students of language with a reference text for the basic notions in the theory of formal grammars and automata, as they keep being referred to in linguistic and psycholinguistic publications; the subject index of this introduction can be used to find definitions of a wide range of technical terms. An appendix has been added with further references to some of the core new developments since this book originally appeared.

Multipass precedence analysis

Abstract: This paper defines a hierarchy of languages which is properly contained in the context sensitive languages and which starts with the context free family. The hierarchy is defined inductively by controlling labeled linear grammars with languages in one family to yield languages in the next larger family. The families of the hierarchy have properties analogous to those of the context free family, in particular, the new mechanism introduced is very suitable for parsing. A language in the n-th family is specified by a sequence of n -- 1 labeled linear grammars and a context free grammar. By assuming that the reversals of the first n -- 1 grammars and the last labeled linear grammar are precedence grammars, the concepts and parsing algorithm of Wirth and Weber extend to yield a parsing algorithm within the hierarchy. This considerably enhances the usefulness of the construction and allows much of the power of the context sensitive languages to become accessible in measured amounts for potential programming applications.