{ "id": "1201.3814", "version": "v1", "published": "2012-01-18T15:08:38.000Z", "updated": "2012-01-18T15:08:38.000Z", "title": "The weights of closed subgroups of a locally compact group", "authors": [ "Salvador Hernández", "Karl H. Hofmann", "Sidney A. Morris" ], "categories": [ "math.GR", "math.GN" ], "abstract": "Let $G$ be an infinite locally compact group and $\\aleph$ a cardinal satisfying $\\aleph_0\\le\\aleph\\le w(G)$ for the weight $w(G)$ of $G$. It is shown that there is a closed subgroup $N$ of $G$ with $w(N)=\\aleph$. Sample consequences are: (1) Every infinite compact group contains an infinite closed metric subgroup. (2) For a locally compact group $G$ and $\\aleph$ a cardinal satisfying $\\aleph_0\\le\\aleph\\le \\lw(G)$, where $\\lw(G)$ is the local weight of $G$, there are either no infinite compact subgroups at all or there is a compact subgroup $N$ of $G$ with $w(N)=\\aleph$. (3) For an infinite abelian group $G$ there exists a properly ascending family of locally quasiconvex group topologies on $G$, say, $(\\tau_\\aleph)_{\\aleph_0\\le \\aleph\\le \\card(G)}$, such that $(G,\\tau_\\aleph)\\hat{\\phantom{m}}\\cong\\hat G$. Items (2) and (3) are shown in Section 5.", "revisions": [ { "version": "v1", "updated": "2012-01-18T15:08:38.000Z" } ], "analyses": { "subjects": [ "22C05", "22D05", "22D35" ], "keywords": [ "closed subgroup", "infinite compact group contains", "infinite locally compact group", "infinite abelian group", "infinite closed metric subgroup" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2012arXiv1201.3814H" } } }