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International Journal of Computer Mathematics, 1997
The present paper investigates the descriptional complexity of multi-sequential grammars with respect to the number of nonterminals. This investigation demonstrates that the family of recursively enumerable languages is characterized by six-nonterminal multi-sequential grammars.
Alexander Meduna
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The present paper investigates the descriptional complexity of multi-sequential grammars with respect to the number of nonterminals. This investigation demonstrates that the family of recursively enumerable languages is characterized by six-nonterminal multi-sequential grammars.
Alexander Meduna
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International Journal of Computer Mathematics, 1997
The family of recursively enumerable languages is characterized by scattered context grammars with four nonterminals. Moreover, this family is characterized by scattered context grammars with three nonterminals if these grammars start their derivations from a word rather than a symbol.
Alexander Meduna
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The family of recursively enumerable languages is characterized by scattered context grammars with four nonterminals. Moreover, this family is characterized by scattered context grammars with three nonterminals if these grammars start their derivations from a word rather than a symbol.
Alexander Meduna
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On characterizations of recursively enumerable languages
Acta Informatica, 1990\textit{V. Geffert} [Theor. Comput. Sci. 62, 235-249 (1988; Zbl 0664.68075)] has shown that each recursively enumerable language L over \(\Sigma\) can be expressed in the form \(L=\{h(x)^{-1}g(x)|\) x in \(\Delta^+\}\cap \Sigma^*\) where \(\Delta\) is an alphabet and g, h is a pair of morphisms.
Michel Latteux, Paavo Turakainen
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Flow languages equal recursively enumerable languages
Acta Informatica, 1981Recently, A.C. Shaw introduced a new class of expressions called flow expressions, and conjectured that the formal descriptive power of flow expressions lies somewhat below context-sensitive grammers. In this paper, we give a negative answer for his conjecture, that is, we show that all recursively enumerable languages may be denoted by flow ...
Toshiro Araki, Nobuki Tokura
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Closure properties for fuzzy recursively enumerable languages and fuzzy recursive languages
Journal of Intelligent & Fuzzy Systems, 2016There are several variations of fuzzy Turing machines in the literature, many of them require a t-norm in order to establish their accepted language. This paper generalize the concept of non-deterministic fuzzy Turing machine - NTFM, replacing the t-norm operator for several aggregation functions.
Antonio Diego Silva Farias +3 more
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Global Syntax and Semantics for Recursively Enumerable Languages
Fundamenta Informaticae, 1981According to (Benson, 1970), a syntax is a category of strings and derivations (modulo similarity) between them. In this paper the semantic domain is an elementary topes. Thus, an interpretation of a syntax is a cofunctor taking strigs to products and derivations to morphisms.
Cristian Calude, Gheorghe Paun
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On Conservative Learning of Recursively Enumerable Languages
2013Conservative partial learning is a variant of partial learning whereby the learner, on a text for a target language L, outputs one index e with L = W e infinitely often and every further hypothesis d is output only finitely often and satisfies \(L \not\subseteq W_d\).
Ziyuan Gao +2 more
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Grammar systems as language analyzers and recursively enumerable languages
1999We consider parallel communicating grammar systems which consist of several grammars and perform derivation steps, where each of the grammars works in a parallel and synchronized manner on its own sentential form, and communication steps, where a transfer of sentential forms is done.
Henning Bordihn +2 more
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J. Autom. Lang. Comb., 1999
We prove that every recursively enumerable language can be generated by a programmed grammar with context-free core rules using unconditional transfer with left-most derivation of type 3 or type 2. Interestingly, we have to give a non-constructive proof of the first mentioned universality result based on Higman's lemma, since finding a transformation ...
Henning Fernau, Frank Stephan 0001
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We prove that every recursively enumerable language can be generated by a programmed grammar with context-free core rules using unconditional transfer with left-most derivation of type 3 or type 2. Interestingly, we have to give a non-constructive proof of the first mentioned universality result based on Higman's lemma, since finding a transformation ...
Henning Fernau, Frank Stephan 0001
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A characterization of recursively enumerable languages
Bull. EATCS, 1991It is shown that each recursively enumerable language \(L\) can be written in the form \(L=\text{red}(L_ 0)\cap V^*\), where red is the reduction operation considered in \textit{H. A. Maurer}, \textit{G. Rozenberg} and \textit{E. Welzl} [Inf. Control 54, 155-185 (1982; Zbl 0523.68065)], \(L_ 0\) is a linear language, and \(V\) is the alphabet of \(L\).
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