{ "id": "1409.7903", "version": "v1", "published": "2014-09-28T13:01:29.000Z", "updated": "2014-09-28T13:01:29.000Z", "title": "The Answers to a Problem and Two Conjectures about OD-Characterization of Finite Groups", "authors": [ "Ali Mahmoudifar", "Behrooz Khosravi" ], "comment": "3 pages", "categories": [ "math.GR" ], "abstract": "In [Akbari and Moghaddamfar, Recognizing by order and degree pattern of some projective special linear groups, {\\it Internat. J. Algebra Comput.}, 2012] the authors possed the following problem: \\\\ {\\bf Problem.} {\\it Is there a simple group which is $k$-fold OD-characterizable for $k\\geq3\\ ?$ } In this paper as the main result we give positive answer to the above problem and we introduce two simple groups which are $k$-fold OD-characterizable such that $k\\geq6$. Also in [R. Kogani-Moghadam and A. R. Moghaddamfar, Groups with the same order and degree pattern, {\\it Science China Mathematics}, 2012], the authors possed two conjectures as follows: \\\\ {\\bf Conjecture 1.} {\\it All alternating groups $A_m$ with $m \\not= 10$ are OD-characterizable.} \\\\ {\\bf Conjecture 2.} {\\it All symmetric groups $S_m$, with $m \\not= 10$, are $n$-fold OD-characterizable, where $n\\in\\{1, 3\\}$.} In this paper we find some alternating and some symmetric groups such that these conjectures are not true for them.", "revisions": [ { "version": "v1", "updated": "2014-09-28T13:01:29.000Z" } ], "analyses": { "keywords": [ "finite groups", "conjecture", "symmetric groups", "simple group", "fold od-characterizable" ], "note": { "typesetting": "TeX", "pages": 3, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1409.7903M" } } }