{ "id": "1709.03937", "version": "v1", "published": "2017-09-12T16:21:38.000Z", "updated": "2017-09-12T16:21:38.000Z", "title": "On separability of Schur rings over abelian p-groups", "authors": [ "Grigory Ryabov" ], "categories": [ "math.CO", "math.GR" ], "abstract": "An $S$-ring (Schur ring) is called separable with respect to a class of $S$-rings $\\mathcal{K}$ if it is determined up to isomorphism in $\\mathcal{K}$ only by the tensor of its structure constants. An abelian group is said to be separable if every $S$-ring over this group is separable with respect to the class of $S$-rings over abelian groups. Let $C_n$ be a cyclic group of order $n$ and $G$ be a noncylic abelian $p$-group. From the previously obtained results it follows that if $G$ is separable then $G$ is isomorphic to $C_p\\times C_{p^k}$ or $C_p\\times C_p\\times C_{p^k}$, where $p\\in \\{2,3\\}$ and $k\\geq 1$. We prove that the groups $D=C_p\\times C_{p^k}$ are separable whenever $p\\in \\{2,3\\}$. From this statement we deduce that a given Cayley graph over $D$ and a given Cayley graph over an arbitrary abelian group one can check whether these graphs are isomorphic in time $|D|^{O(1)}$.", "revisions": [ { "version": "v1", "updated": "2017-09-12T16:21:38.000Z" } ], "analyses": { "subjects": [ "05E30", "05C60", "20B35" ], "keywords": [ "abelian p-groups", "schur ring", "cayley graph", "separability", "arbitrary abelian group" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }