Abstract
For a word w and a partial word u of the same length, say w derives u if w can be transformed into u by inserting holes, i.e., by replacing letters with don’t cares, with the restriction that no two holes may be within distance two. We present and prove a necessary and sufficient condition for a word of even length (at least eight) to not derive any squares (such word is called non-squareable). The condition can be decided in O(n) time, where n is the length of the word.
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Blanchet-Sadri, F., Rashin, A. (2015). Squareable Words. In: Potapov, I. (eds) Developments in Language Theory. DLT 2015. Lecture Notes in Computer Science(), vol 9168. Springer, Cham. https://doi.org/10.1007/978-3-319-21500-6_10
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DOI: https://doi.org/10.1007/978-3-319-21500-6_10
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