Now showing items 36-40 of 40

    • A Ternary Square-free Sequence Avoiding Factors Equivalent to abcacba 

      Currie, James D. (The Electronic Journal of Combinatorics, 2016-05-27)
      We solve a problem of Petrova, finalizing the classification of letter patterns avoidable by ternary square-free words; we show that there is a ternary square-free word avoiding letter pattern xyzxzyx. In fact, we characterize ...
    • There are Ternary Circular Square-Free Words of Length n for n ≥ 18 

      Currie, James D. (The Electronic Journal of Combinatorics, 2002-10-11)
      There are circular square-free words of length n on three symbols for n≥18. This proves a conjecture of R. J. Simpson.
    • There Exist Binary Circular 5/2+ Power Free Words of Every Length 

      Aberkane, Ali; Currie, James D. (The Electronic Journal of Combinatorics, 2004-01-23)
      We show that there exist binary circular 5/2+ power free words of every length.
    • Unary patterns under permutations 

      Currie, James D.; Nowotka, Dirk; Manea, Florin; Reshadi, Kamellia (Elsevier, 2018-06-04)
      Thue characterized completely the avoidability of unary patterns. Adding function variables gives a general setting capturing avoidance of powers, avoidance of patterns with palindromes, avoidance of powers under coding, ...
    • Words without Near-Repetitions 

      Currie, J.; Bendor-Samuel, A. (Canadian Mathematical Society, 1992-06-01)
      We find an infinite word w on four symbols with the following property: Two occurrences of any block in w must be separated by more than the length of the block. That is, in any subword of w of the form xyx, the length of ...