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Radix enumeration of rational languages

Pierre-Yves Angrand, Jacques Sakarovitch (2010)

RAIRO - Theoretical Informatics and Applications

We prove that the function that maps a word of a rational language onto its successor for the radix order in this language is a finite union of co-sequential functions.

Random generation for finitely ambiguous context-free languages

Alberto Bertoni, Massimiliano Goldwurm, Massimo Santini (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We prove that a word of length n from a finitely ambiguous context-free language can be generated at random under uniform distribution in O ( n 2 log n ) time by a probabilistic random access machine assuming a logarithmic cost criterion. We also show that the same problem can be solved in polynomial time for every language accepted by a polynomial time 1 -NAuxPDA with polynomially bounded ambiguity.

Random Generation for Finitely Ambiguous Context-free Languages

Alberto Bertoni, Massimiliano Goldwurm, Massimo Santini (2010)

RAIRO - Theoretical Informatics and Applications

We prove that a word of length n from a finitely ambiguous context-free language can be generated at random under uniform distribution in O(n2 log n) time by a probabilistic random access machine assuming a logarithmic cost criterion. We also show that the same problem can be solved in polynomial time for every language accepted by a polynomial time 1-NAuxPDA with polynomially bounded ambiguity.

Reaction automata working in sequential manner

Fumiya Okubo (2014)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Based on the formal framework of reaction systems by Ehrenfeucht and Rozenberg [Fund. Inform. 75 (2007) 263–280], reaction automata (RAs) have been introduced by Okubo et al. [Theoret. Comput. Sci. 429 (2012) 247–257], as language acceptors with multiset rewriting mechanism. In this paper, we continue the investigation of RAs with a focus on the two manners of rule application: maximally parallel and sequential. Considering restrictions on the workspace and the λ-input mode, we introduce the corresponding...

Recognizing when heuristics can approximate minimum vertex covers is complete for parallel access to NP

Edith Hemaspaandra, Jörg Rothe, Holger Spakowski (2006)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

For both the edge deletion heuristic and the maximum-degree greedy heuristic, we study the problem of recognizing those graphs for which that heuristic can approximate the size of a minimum vertex cover within a constant factor of r , where r is a fixed rational number. Our main results are that these problems are complete for the class of problems solvable via parallel access to NP . To achieve these main results, we also show that the restriction of the vertex cover problem to those graphs for which...

Recognizing when heuristics can approximate minimum vertex covers is complete for parallel access to NP

Edith Hemaspaandra, Jörg Rothe, Holger Spakowski (2010)

RAIRO - Theoretical Informatics and Applications

For both the edge deletion heuristic and the maximum-degree greedy heuristic, we study the problem of recognizing those graphs for which that heuristic can approximate the size of a minimum vertex cover within a constant factor of r, where r is a fixed rational number. Our main results are that these problems are complete for the class of problems solvable via parallel access to NP. To achieve these main results, we also show that the restriction of the vertex cover problem to those...

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