Displaying similar documents to “Hierarchies and reducibilities on regular languages related to modulo counting”

Extending regular expressions with homomorphic replacement

Henning Bordihn, Jürgen Dassow, Markus Holzer (2010)

RAIRO - Theoretical Informatics and Applications

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We define H- and EH-expressions as extensions of regular expressions by adding homomorphic and iterated homomorphic replacement as new operations, resp. The definition is analogous to the extension given by Gruska in order to characterize context-free languages. We compare the families of languages obtained by these extensions with the families of regular, linear context-free, context-free, and EDT0L languages. Moreover, relations to language families based on patterns, multi-patterns,...

Hierarchies and reducibilities on regular languages related to modulo counting

Victor L. Selivanov (2008)

RAIRO - Theoretical Informatics and Applications

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We discuss some known and introduce some new hierarchies and reducibilities on regular languages, with the emphasis on the quantifier-alternation and difference hierarchies of the quasi-aperiodic languages. The non-collapse of these hierarchies and decidability of some levels are established. Complete sets in the levels of the hierarchies under the polylogtime and some quantifier-free reducibilities are found. Some facts about the corresponding degree structures are established. As...

Consensual languages and matching finite-state computations

Stefano Crespi Reghizzi, Pierluigi San Pietro (2011)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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An ever present, common sense idea in language modelling research is that, for a word to be a valid phrase, it should comply with multiple constraints at once. A new language definition model is studied, based on agreement or consensus between similar strings. Considering a regular set of strings over a bipartite alphabet made by pairs of unmarked/marked symbols, a match relation is introduced, in order to specify when such strings agree. Then a regular set over the bipartite alphabet...

Consensual languages and matching finite-state computations

Stefano Crespi Reghizzi, Pierluigi San Pietro (2011)

RAIRO - Theoretical Informatics and Applications

Similarity:

An ever present, common sense idea in language modelling research is that, for a word to be a valid phrase, it should comply with multiple constraints at once. A new language definition model is studied, based on agreement or consensus between similar strings. Considering a regular set of strings over a bipartite alphabet made by pairs of unmarked/marked symbols, a match relation is introduced, in order to specify when such strings agree. Then a regular set over the bipartite alphabet...

On the expressive power of the shuffle operator matched with intersection by regular sets

Joanna Jȩdrzejowicz, Andrzej Szepietowski (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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We investigate the complexity of languages described by some expressions containing shuffle operator and intersection. We show that deciding whether the shuffle of two words has a nonempty intersection with a regular set (or fulfills some regular pattern) is NL-complete. Furthermore we show that the class of languages of the form L ∩ R , with a shuffle language L and a regular language R , contains non-semilinear languages and does not form a family of mildly context- sensitive languages. ...

Complexity results for prefix grammars

Markus Lohrey, Holger Petersen (2005)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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Resolving an open problem of Ravikumar and Quan, we show that equivalence of prefix grammars is complete in PSPACE. We also show that membership for these grammars is complete in P (it was known that this problem is in P) and characterize the complexity of equivalence and inclusion for monotonic grammars. For grammars with several premises we show that membership is complete in EXPTIME and hard for PSPACE for monotonic grammars.