{ "id": "1804.04634", "version": "v1", "published": "2018-04-12T17:06:03.000Z", "updated": "2018-04-12T17:06:03.000Z", "title": "One application of the $σ$-local formations of finite groups", "authors": [ "Zhang Chi", "Alexander N. Skiba" ], "comment": "12 pages", "categories": [ "math.GR" ], "abstract": "Throughout this paper, all groups are finite. Let $\\sigma =\\{\\sigma_{i} | i\\in I \\}$ be some partition of the set of all primes $\\Bbb{P}$. If $n$ is an integer, the symbol $\\sigma (n)$ denotes the set $\\{\\sigma_{i} |\\sigma_{i}\\cap \\pi (n)\\ne \\emptyset \\}$. The integers $n$ and $m$ are called $\\sigma$-coprime if $\\sigma (n)\\cap \\sigma (m)=\\emptyset$. Let $t > 1$ be a natural number and let $\\mathfrak{F}$ be a class of groups. Then we say that $\\mathfrak{F}$ is $\\Sigma_{t}^{\\sigma}$-closed provided $\\mathfrak{F}$ contains each group $G$ with subgroups $A_{1}, \\ldots , A_{t}\\in \\mathfrak{F}$ whose indices $|G:A_{1}|$, $\\ldots$, $|G:A_{t}|$ are pairwise $\\sigma$-coprime. In this paper, we study $\\Sigma_{t}^{\\sigma}$-closed classes of finite groups.", "revisions": [ { "version": "v1", "updated": "2018-04-12T17:06:03.000Z" } ], "analyses": { "subjects": [ "20D10", "20D15", "20D20" ], "keywords": [ "finite groups", "local formations", "application", "natural number", "throughout" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable" } } }