Orientable sequences over non-binary alphabets
Combinatorics
2026-03-20 v2
Abstract
We describe new, simple, recursive methods of construction for orientable sequences over an arbitrary finite alphabet, i.e. periodic sequences in which any sub-sequence of n consecutive elements occurs at most once in a period in either direction. In particular we establish how two variants of a generalised Lempel homomorphism can be used to recursively construct such sequences, generalising previous work on the binary case. We also derive an upper bound on the period of an orientable sequence.
Cite
@article{arxiv.2407.14866,
title = {Orientable sequences over non-binary alphabets},
author = {Abbas Alhakim and Chris J. Mitchell and Janusz Szmidt and Peter R. Wild},
journal= {arXiv preprint arXiv:2407.14866},
year = {2026}
}
Comments
Minor bugs fixed