English

Separability of Schur rings over abelian groups of odd order

Combinatorics 2020-12-29 v1 Group Theory

Abstract

An SS-ring (a Schur ring) is said to be separable with respect to a class of groups K\mathcal{K} if every algebraic isomorphism from the SS-ring in question to an SS-ring over a group from K\mathcal{K} is induced by a combinatorial isomorphism. A finite group GG is said to be separable with respect to K\mathcal{K} if every SS-ring over GG is separable with respect to K\mathcal{K}. We prove that every abelian group GG of order 9p9p, where pp is a prime, is separable with respect to the class of all finite abelian groups. Modulo previously obtained results, this completes a classification of noncyclic abelian groups of odd order that are separable with respect to the class of all finite abelian groups. Also this implies that the Weisfeiler-Leman dimension of the class of Cayley graphs over GG is at most 2.

Keywords

Cite

@article{arxiv.1912.07279,
  title  = {Separability of Schur rings over abelian groups of odd order},
  author = {Grigory Ryabov},
  journal= {arXiv preprint arXiv:1912.07279},
  year   = {2020}
}

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17 pages