{ "id": "0903.1488", "version": "v2", "published": "2009-03-09T07:13:57.000Z", "updated": "2009-04-09T11:34:50.000Z", "title": "The diffeotopy group of S^1 \\times S^2 via contact topology", "authors": [ "Fan Ding", "Hansjörg Geiges" ], "comment": "17 pages, 10 figures; v2: simplified proof of Lemma 6 (and extension to higher dimensions)", "journal": "Compos. Math. 146 (2010), 1096-1112", "doi": "10.1112/S0010437X09004606", "categories": [ "math.GT", "math.SG" ], "abstract": "As shown by H. Gluck in 1962, the diffeotopy group of S^1 \\times S^2 is isomorphic to Z_2 + Z_2 + Z_2. Here an alternative proof of this result is given, relying on contact topology. We then discuss two applications to contact topology: (i) it is shown that the fundamental group of the space of contact structures on S^1 \\times S^2, based at the standard tight contact structure, is isomorphic to the integers; (ii) inspired by previous work of M. Fraser, an example is given of an integer family of Legendrian knots in S^1 \\times S^2 # S^1 \\times S^2 (with its standard tight contact structure) that can be distinguished with the help of contact surgery, but not by the classical invariants (topological knot type, Thurston-Bennequin invariant, and rotation number).", "revisions": [ { "version": "v2", "updated": "2009-04-09T11:34:50.000Z" } ], "analyses": { "subjects": [ "57R50", "57R52", "53D10", "57M25" ], "keywords": [ "contact topology", "diffeotopy group", "standard tight contact structure", "legendrian knots", "isomorphic" ], "tags": [ "journal article" ], "note": { "typesetting": "TeX", "pages": 17, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2009arXiv0903.1488D" } } }