Displaying similar documents to “Regular languages definable by Lindström quantifiers”

On Varieties of Literally Idempotent Languages

Ondřej Klíma, Libor Polák (2008)

RAIRO - Theoretical Informatics and Applications

Similarity:

A language is literally idempotent in case that if and only if , for each , . Varieties of literally idempotent languages result naturally by taking all literally idempotent languages in a classical (positive) variety or by considering a certain closure operator on classes of languages. We initiate the systematic study of such varieties. Various classes of literally idempotent languages can be characterized using syntactic methods. A starting example is the class of all finite unions...

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

Similarity:

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. ...

Extending regular expressions with homomorphic replacement

Henning Bordihn, Jürgen Dassow, Markus Holzer (2010)

RAIRO - Theoretical Informatics and Applications

Similarity:

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,...