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An Elementary Proof of the Õ(n1/3) Bound for Separating Words
Abstract
For two distinct binary words of length n, the separating words problem asks for a small deterministic finite automaton that accepts exactly one of them. Chase proved a Õ(n1/3) upper bound using a complex-analytic estimate for sparse polynomials. We replace that estimate by a finite-difference argument and a second-order real recurrence cutoff. The resulting elementary proof gives an explicit bound of O(n1/3(log n)7/3) states.
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BibTeX
@misc{xu2026elementary,
title = {{An Elementary Proof of the $\widetilde O(n^1/3)$ Bound for Separating Words}},
author = {Chen Xu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08191},
eprint = {2609.08191},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08191},
}
RIS
TY - UNPB
TI - An Elementary Proof of the Õ(n^1/3) Bound for Separating Words
AU - Chen Xu
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08191
UR - https://arxiv.org/abs/2609.08191
AB - For two distinct binary words of length n, the separating words problem asks for a small deterministic finite automaton that accepts exactly one of them. Chase proved a Õ(n^1/3) upper bound using a complex-analytic estimate for sparse polynomials. We replace that estimate by a finite-difference argument and a second-order real recurrence cutoff. The resulting elementary proof gives an explicit bound of O(n^1/3(log n)^7/3) states.
ER -