{ "id": "1108.2409", "version": "v2", "published": "2011-08-03T03:59:05.000Z", "updated": "2012-08-14T14:31:07.000Z", "title": "Correction of a theorem on the symmetric group generated by transvections", "authors": [ "Hau-wen Huang" ], "comment": "7 pages", "categories": [ "math.GR", "math.CO" ], "abstract": "Let $V$ denote a vector space over two-element field $\\mathbb F_2$ with finite positive dimension and endowed with a symplectic form $B.$ Let ${\\rm SL}(V)$ denote the special linear group of $V.$ Let $S$ denote a subset of $V.$ Define $Tv(S)$ as the subgroup of ${\\rm SL}(V)$ generated by the transvections with direction $\\alpha$ for all $\\alpha\\in S.$ Define $G(S)$ as the graph whose vertex set is $S$ and where $\\alpha,\\beta\\in S$ are connected whenever $B(\\alpha,\\beta)=1.$ A well-known theorem states that under the assumption that $S$ spans $V,$ the following (i), (ii) are equivalent: (i) $Tv(S)$ is isomorphic to a symmetric group. (ii) $G(S)$ is a claw-free block graph. We give an example which shows that this theorem is not true. We give a modification of this theorem as follows. Assume that $S$ is a linearly independent set of $V$ and no element of $S$ is in the radical of $V.$ Then the above (i), (ii) are equivalent.", "revisions": [ { "version": "v2", "updated": "2012-08-14T14:31:07.000Z" } ], "analyses": { "keywords": [ "symmetric group", "transvections", "correction", "claw-free block graph", "well-known theorem states" ], "note": { "typesetting": "TeX", "pages": 7, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1108.2409H" } } }