{ "id": "1406.6067", "version": "v2", "published": "2014-06-23T20:00:48.000Z", "updated": "2014-07-29T17:05:37.000Z", "title": "Order complexes of coset posets of finite groups are not contractible", "authors": [ "John Shareshian", "Russ Woodroofe" ], "comment": "16 pages. v2 fixes minor errors", "categories": [ "math.CO", "math.GR" ], "abstract": "We show that the order complex of the poset of all cosets of all proper subgroups of a finite group $G$ is never $\\mathbb{F}_{2}$-acyclic and therefore never contractible. This settles a question of K. S. Brown.", "revisions": [ { "version": "v2", "updated": "2014-07-29T17:05:37.000Z" } ], "analyses": { "subjects": [ "05E45", "20E99", "06B30" ], "keywords": [ "finite group", "coset posets", "order complexes", "contractible" ], "note": { "typesetting": "TeX", "pages": 16, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1406.6067S" } } }