Binary Periodic Synchronizing Sequences


In this article, we consider words over f0; 1g of length l 2. The autodistance of such a word is the lowest among the Hamming distances between the word and its images by circular permutations other than identity; the word’s reverse autodistance is the highest among these distances. For each l 2, we study the words of length l whose autodistance and reverse autodistance are close to l=2 (we call such words synchronizing sequences). We establish, for every l 3, an upper bound on the autodistance of words of length l. This upper bound, called up(l), is very close to l=2. We briefly describe the maximal period linear recurring sequences, a previously known family of words over f0; 1g achieving the upper bound up(l) for l = 2 1. Examples of words whose autodistance and reverse autodistance are both equal or close to up(l) are discussed; we describe the method (based on simulated annealing) which permitted the examples to be found. We prove that, for l large enough, an arbitrary majority of words of length l has both its autodistance and its reverse autodistance very close to up(l).

DOI: 10.1016/0304-3975(92)90233-6

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@article{Skubiszewski1992BinaryPS, title={Binary Periodic Synchronizing Sequences}, author={Marcin Skubiszewski}, journal={Theor. Comput. Sci.}, year={1992}, volume={102}, pages={253-281} }