{ "id": "1705.02360", "version": "v1", "published": "2017-05-05T18:34:07.000Z", "updated": "2017-05-05T18:34:07.000Z", "title": "Groups in which each subgroup is commensurable with a normal subgroup", "authors": [ "Carlo Casolo", "Ulderico Dardano", "Silvana Rinauro" ], "categories": [ "math.GR" ], "abstract": "A group G is a cn-group if for each subgroup H of G there exists a normal subgroup N of G such that the index of both H and N in HN is finite. The class of cn-groups contains properly the classes of core- finite groups and that of groups in which each subgroup has finite index in a normal subgroup. In the present paper it is shown that a cn-group whose periodic images are locally finite is finite-by-abelian-by-finite. Such groups are then described into some details by considering automorphisms of abelian groups. Finally, it is shown that if G is a locally graded group with the property that the above index is bounded independently of H, then G is finite-by-abelian-by-finite.", "revisions": [ { "version": "v1", "updated": "2017-05-05T18:34:07.000Z" } ], "analyses": { "keywords": [ "normal subgroup", "abelian groups", "finite index", "cn-groups contains", "finite-by-abelian-by-finite" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }