{ "id": "0901.0175", "version": "v1", "published": "2009-01-01T11:24:45.000Z", "updated": "2009-01-01T11:24:45.000Z", "title": "Convergent sequences in minimal groups", "authors": [ "Dmitri Shakhmatov" ], "categories": [ "math.GN", "math.GR" ], "abstract": "A Hausdorff topological group G is minimal if every continuous isomorphism f : G --> H between G and a Hausdorff topological group H is open. Clearly, every compact Hausdorff group is minimal. It is well known that every infinite compact Hausdorff group contains a non-trivial convergent sequence. We extend this result to minimal abelian groups by proving that every infinite minimal abelian group contains a non-trivial convergent sequence. Furthermore, we show that \"abelian\" is essential and cannot be dropped. Indeed, for every uncountable regular cardinal kappa we construct a Hausdorff group topology T_kappa on the free group F(kappa) with kappa many generators having the following properties: (i) (F(kappa), T_kappa) is a minimal group; (ii) every subset of F(kappa) of size less than kappa is T_kappa-discrete (and thus also T_kappa-closed); (iii) there are no non-trivial proper T_kappa-closed normal subgroups of F(kappa). In particular, all compact subsets of (F(kappa), T_kappa) are finite, and every Hausdorff quotient group of (F(kappa), T_kappa) is minimal (that is, (F(kappa), T_kappa) is totally minimal).", "revisions": [ { "version": "v1", "updated": "2009-01-01T11:24:45.000Z" } ], "analyses": { "subjects": [ "22A05", "22C05", "54A10", "54A20", "54A25", "54D25", "54H11" ], "keywords": [ "minimal group", "non-trivial convergent sequence", "infinite compact hausdorff group contains", "hausdorff topological group", "infinite minimal abelian group contains" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2009arXiv0901.0175S" } } }