Time varying pushdown automata
01 Jan 1988-International Journal of Computer Mathematics (Gordon and Breach Science Publishers)-Vol. 24, pp 223-236
TL;DR: It is seen that periodically time varying pushdown automata accept exactly the class of context-free languages.
Abstract: Time varying pushdown automata (PDA) are defined and equivalence between two modes of acceptance shown. It is seen that periodically time varying pushdown automata accept exactly the class of context-free languages. Time varying generalized PDA are defined and their equivalence to terminal weighted context free grammars in GNF shown. It is shown that TVGPDA can be simulated by TVPDA. Thus TVPDA give another machine characterization of recursively enumerable sets.
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01 Jan 2007
TL;DR: In this article, an artigo levanta uma parcela significativa da litera-tura publicada em torno da adapta tividade e de assuntos associa-dos.
Abstract: Resumo Esta publicacao procura analisar a evolucao da a-daptatividade e de suas aplicacoes. Neste contexto, o termo se refere a propriedade que um sistema ou um dispositivo apresenta de modificar suas proprias regras de funcionamento, em funcao de seu historico, sem interferencia externa. Entende-se como tecnologia adaptativa a aplicacao da adaptatividade com fins praticos. Este artigo levanta uma parcela significativa da litera-tura publicada em torno da adapta tividade e de assuntos associa-dos e procura relacionar as obras segundo os temas, e cada tema, segundo a cronologia de publicacao. Palavras-chave Adaptatividade, Dispositivos Adaptativos, Sistemas Adaptativos, Sist emas Automodificaveis.
18 citations
TL;DR: It is shown that synchronized extension systems can be successfully used to simulate timing mechanisms incorporated into grammars and automata and the concept of a time-varying code as a natural generalization of L-codes is introduced.
Abstract: We show that synchronized extension systems [17] can be successfully used to simulate timing mechanisms incorporated into grammars and automata [3, v 7-9, v 12]. Further, we introduce the concept of a time-varying code as a natural generalization of L-codes, and the relationship with classical codes, gsm codes and SE-codes is established. Finally, an algorithm for testing the time-varying code property in case of periodicity is given.
12 citations
TL;DR: In this paper, the recognition capabilities of CA and TVCA are compared, and the power of this implicit query mechanism is compared with the traditional oracle access in Turing machines.
Abstract: Cellular automata (CA) are parallel language recognition devices. In this paper, the notion of a time-varying CA (TVCA) is introduced. In a TVCA, the transition function can vary with time, and the variation is controlled by a prespecified language. This language can be viewed as an oracle to which the TVCA makes implicit queries; thus TVCA provide a mechanism for defining relativised CA. In this paper, the recognition capabilities of CA and TVCA are compared. TVCA as relativised CA are formalised, and the power of this implicit query mechanism is compared with the traditional oracle access in Turing machines.
7 citations
TL;DR: This paper gathers a significant collection of available publications on adaptivity and related topics and organizes the collected works according to their subject, and the publications on each subject, according to the chronological sequence of their publication.
Abstract: The present paper is an attempt to survey the evolution of adaptivity and its applications. In this context, adaptivity is a term that refers to the property exhibited by some system or device that is able to self-modify its own set of operation rules, driven exclusively by its history, without the help of any external active element. Adaptive technology refers to the application of adaptivity as a tool for solving practical problems. This paper gathers a significant collection of available publications on adaptivity and related topics. It organizes the collected works according to their subject, and the publications on each subject, according to the chronological sequence of their publication.
5 citations
TL;DR: This article presents a line of research, in adaptive automata, based in results for context-free adaptive grammars with appearance checking, and proposes a strategy to deduce a restricted version of the general result.
Abstract: This article presents a line of research, in adaptive automata, based in results for context-free adaptive grammars with appearance checking. The grammatical results are described and exemplified and a strategy is proposed in order to obtain analogous results for the case of the adaptive automata. This strategy is then applied successfully to deduce a restricted version, for the case of the adaptative automata, of the general result for context-free adaptive grammars with appearance checking.
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Book•
01 Jan 1979
TL;DR: This book is a rigorous exposition of formal languages and models of computation, with an introduction to computational complexity, appropriate for upper-level computer science undergraduates who are comfortable with mathematical arguments.
Abstract: This book is a rigorous exposition of formal languages and models of computation, with an introduction to computational complexity. The authors present the theory in a concise and straightforward manner, with an eye out for the practical applications. Exercises at the end of each chapter, including some that have been solved, help readers confirm and enhance their understanding of the material. This book is appropriate for upper-level computer science undergraduates who are comfortable with mathematical arguments.
13,779 citations
13 Dec 1984
TL;DR: A terminal weighted grammar is defined where the terminal generated at any step of a derivation is defined as a function of time and it is seen that terminal weighted regular grammars generate exactly the class of recursively enumerable sets.
Abstract: Motivated by the idea of describing parquet deformations using grammars, we define in this paper a terminal weighted grammar where the terminal generated at any step of a derivation is defined as a function of time. It is seen that terminal weighted regular grammars generate exactly the class of recursively enumerable sets. Terminal weighted matrix grammars are used to describe parquet deformations. The hierarchy of families generated by putting various restrictions on the functions is studied.
8 citations
01 Apr 1985-Graphical Models \/graphical Models and Image Processing \/computer Vision, Graphics, and Image Processing
TL;DR: A terminal weighted grammar is defined, where the terminal generated at any step of a derivation is defined as a function of time, and it is seen that terminal weighted regular grammars generate exactly the class of recursively enumerable sets.
Abstract: Motivated by the idea of describing parquet deformations using grammars and also of describing an infinite number of terminals starting with only a finite set, this paper defines a terminal weighted grammar, where the terminal generated at any step of a derivation is defined as a function of time It is seen that terminal weighted regular grammars generate exactly the class of recursively enumerable sets Terminal weighted matrix grammars are used to describe parquet deformations The extension of terminal weights to array grammars is also discussed
7 citations
TL;DR: This paper considers two machine models equivalent in power to Turing machines and shows their equivalence to terminal weighted regular grammars, thus proving that time varying generalized finite automata have the same power as Turing machines.
Abstract: In this paper, we consider two machine models equivalent in power to Turing machines. Time varying finite automata are defined and it is shown that time varying nondeterministic finite automata are equivalent to time varying deterministic finite automata. But, we find that, when e-moves are introduced, the power is increased to that of Turing machines. Equivalence between time varying regular grammars [6] and time varying nondeterministic finite automata with e-moves is shown. We also consider time varying generalized finite automata and show their equivalence to terminal weighted regular grammars [5], thus proving that time varying generalized finite automata have the same power as Turing machines.
7 citations