{ "id": "1012.4177", "version": "v1", "published": "2010-12-19T16:00:25.000Z", "updated": "2010-12-19T16:00:25.000Z", "title": "A Kronecker-Weyl theorem for subsets of abelian groups", "authors": [ "Dikran Dikranjan", "Dmitri Shakhmatov" ], "journal": "Advances in Mathematics, 226 (2011), 4776-4795", "doi": "10.1016/j.aim.2010.12.016", "categories": [ "math.GR", "math.DS", "math.GN", "math.LO", "math.NT" ], "abstract": "Let N be the set of non-negative integer numbers, T the circle group and c the cardinality of the continuum. Given an abelian group G of size at most 2^c and a countable family F of infinite subsets of G, we construct \"Baire many\" monomorphisms p: G --> T^c such that p(E) is dense in {y in T^c : ny=0} whenever n in N, E in F, nE={0} and {x in E: mx=g} is finite for all g in G and m such that n=mk for some k in N--{1}. We apply this result to obtain an algebraic description of countable potentially dense subsets of abelian groups, thereby making a significant progress towards a solution of a problem of Markov going back to 1944. A particular case of our result yields a positive answer to a problem of Tkachenko and Yaschenko. Applications to group actions and discrete flows on T^c, diophantine approximation, Bohr topologies and Bohr compactifications are also provided.", "revisions": [ { "version": "v1", "updated": "2010-12-19T16:00:25.000Z" } ], "analyses": { "subjects": [ "20K30", "03E15", "11K36", "11K60", "22A05", "37B05", "54D65", "54E52" ], "keywords": [ "abelian group", "kronecker-weyl theorem", "bohr compactifications", "non-negative integer numbers", "infinite subsets" ], "tags": [ "journal article" ], "publication": { "publisher": "Elsevier", "journal": "Adv. Math." }, "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2010arXiv1012.4177D" } } }