{ "id": "1611.01313", "version": "v1", "published": "2016-11-04T10:34:19.000Z", "updated": "2016-11-04T10:34:19.000Z", "title": "Narain Gupta's three normal subgroup problem and group homology", "authors": [ "Roman Mikhailov", "Inder Bir S. Passi" ], "comment": "20 pages", "categories": [ "math.GR", "math.KT" ], "abstract": "This paper is about application of various homological methods to classical problems in the theory of group rings. It is shown that the third homology of groups plays a key role in Narain Gupta's three normal subgroup problem. For a free group $F$ and its normal subgroups $R,\\,S,\\,T,$ and the corresponding ideals in the integral group ring $\\mathbb Z[F]$, ${\\bf r}=(R-1)\\mathbb Z[F],\\ {\\bf s}=(S-1)\\mathbb Z[F],\\ {\\bf t}=(T-1)\\mathbb Z[F],$ a complete description of the normal subgroup $F\\cap (1+{\\bf rst})$ is given, provided $R\\subseteq T$ and the third and the fourth homology groups of $R/R\\cap S$ are torsion groups.", "revisions": [ { "version": "v1", "updated": "2016-11-04T10:34:19.000Z" } ], "analyses": { "keywords": [ "normal subgroup problem", "narain guptas", "group homology", "fourth homology groups", "torsion groups" ], "note": { "typesetting": "TeX", "pages": 20, "language": "en", "license": "arXiv", "status": "editable" } } }