{ "id": "1912.07279", "version": "v1", "published": "2019-12-16T10:21:16.000Z", "updated": "2019-12-16T10:21:16.000Z", "title": "Separability of Schur rings over abelian groups of odd order", "authors": [ "Grigory Ryabov" ], "comment": "17 pages", "categories": [ "math.CO", "math.GR" ], "abstract": "An $S$-ring (a Schur ring) is said to be separable with respect to a class of groups $\\mathcal{K}$ if every algebraic isomorphism from the $S$-ring in question to an $S$-ring over a group from $\\mathcal{K}$ is induced by a combinatorial isomorphism. A finite group $G$ is said to be separable with respect to $\\mathcal{K}$ if every $S$-ring over $G$ is separable with respect to $\\mathcal{K}$. We prove that every abelian group $G$ of order $9p$, where $p$ 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 $G$ is at most 2.", "revisions": [ { "version": "v1", "updated": "2019-12-16T10:21:16.000Z" } ], "analyses": { "subjects": [ "05E30", "05C60", "20B35" ], "keywords": [ "odd order", "schur ring", "finite abelian groups", "separability", "noncyclic abelian groups" ], "note": { "typesetting": "TeX", "pages": 17, "language": "en", "license": "arXiv", "status": "editable" } } }