Browsing James D. Currie by Title
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On avoidability of formulas with reversal
(EDP Sciences, 20180213)While a characterization of unavoidable formulas (without reversal) is wellknown, little is known about the avoidability of formulas with reversal in general. In this article, we characterize the unavoidable formulas ... 
Squarefree Words with Squarefree Selfshuffles
(The Electronic Journal of Combinatorics, 20140112)We answer a question of Harju: For every n ≥ 3 there is a squarefree ternary word of length n with a squarefree selfshuffle. 
Suffix conjugates for a class of morphic subshifts
(Cambridge University Press, 201509)Let A be a finite alphabet and f: A^* > A^* be a morphism with an iterative fixed point f^\omega(\alpha), where \alpha{} is in A. Consider the subshift (X, T), where X is the shift orbit closure of f^\omega(\alpha) and ... 
A Ternary Squarefree Sequence Avoiding Factors Equivalent to abcacba
(The Electronic Journal of Combinatorics, 20160527)We solve a problem of Petrova, finalizing the classification of letter patterns avoidable by ternary squarefree words; we show that there is a ternary squarefree word avoiding letter pattern xyzxzyx. In fact, we characterize ... 
There are Ternary Circular SquareFree Words of Length n for n ≥ 18
(The Electronic Journal of Combinatorics, 20021011)There are circular squarefree 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
(The Electronic Journal of Combinatorics, 20040123)We show that there exist binary circular 5/2+ power free words of every length. 
Unary patterns under permutations
(Elsevier, 20180604)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 NearRepetitions
(Canadian Mathematical Society, 19920601)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 ...