Name of the Marshall Hall paper in which he proved that the intersection of all subgroups of a fixed finite index is again finite index? - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-22T03:55:58Z http://mathoverflow.net/feeds/question/15420 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/15420/name-of-the-marshall-hall-paper-in-which-he-proved-that-the-intersection-of-all-s Name of the Marshall Hall paper in which he proved that the intersection of all subgroups of a fixed finite index is again finite index? Dave 2010-02-16T03:56:42Z 2010-02-16T06:12:39Z <p>can someone please tell me? I couldn't find a reference in the paper I was reading.</p> http://mathoverflow.net/questions/15420/name-of-the-marshall-hall-paper-in-which-he-proved-that-the-intersection-of-all-s/15423#15423 Answer by Jason Dyer for Name of the Marshall Hall paper in which he proved that the intersection of all subgroups of a fixed finite index is again finite index? Jason Dyer 2010-02-16T04:23:59Z 2010-02-16T04:23:59Z <p>Subgroups of finite index in free groups. Canadian J.Math., 1:187–190, 1949.</p> http://mathoverflow.net/questions/15420/name-of-the-marshall-hall-paper-in-which-he-proved-that-the-intersection-of-all-s/15431#15431 Answer by david mccune for Name of the Marshall Hall paper in which he proved that the intersection of all subgroups of a fixed finite index is again finite index? david mccune 2010-02-16T06:12:39Z 2010-02-16T06:12:39Z <p>Thanks for the help.</p>