On the expressive power of the shuffle operator matched with intersection by regular sets
Joanna Jędrzejowicz, Andrzej Szepietowski · RAIRO - Theoretical Informatics and Applications · 2001
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 , 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.