Browsing Narad Rampersad by Title

Now showing items 6-9 of 9

    • Least Periods of Factors of Infinite Words 

      Currie, James D.; Saari, Kalle (EDP Sciences, 2009)
      We show that any positive integer is the least period of a factor of the Thue-Morse word. We also characterize the set of least periods of factors of a Sturmian word. In particular, the corresponding set for the Fibonacci ...

    • Multi-dimensional sets recognizable in all abstract numeration systems 

      Charlier, Émilie; Lacroix, Anne; Rampersad, Narad (EDP Sciences, 2011)
      We prove that the subsets of Nd that are S-recognizable for all abstract numeration systems S are exactly the 1-recognizable sets. This generalizes a result of Lecomte and Rigo in the one-dimensional setting.

    • On avoidability of formulas with reversal 

      Currie, James D.; Mol, Lucas; Rampersad, Narad (EDP Sciences, 2018-02-13)
      While a characterization of unavoidable formulas (without reversal) is well-known, little is known about the avoidability of formulas with reversal in general. In this article, we characterize the unavoidable formulas ...

    • Shuffling and unshuffling 

      Henshall, Dane; Rampersad, Narad; Shallit, Jeffrey (Bulletin of the European Association for Theoretical Computer Science, 2012)
      We consider various shuffling and unshuffling operations on languages and words, and examine their closure properties. Although the main goal is to provide some good and novel exercises and examples for undergraduate formal ...