2004/11/03 by Delaram Kahrobaei, Kahrobaei, Delaram
Mathematics · #20E05 #Advanced Differential Equations and Dynamical Systems #Advanced Topology and Set Theory #FOS: Mathematics #Group Theory (math.GR) #math.GR #msc:20E05
paper · pdf · doi:10.48550/arxiv.math/0411076
2 pages. to appear
arxiv created 2004/11/03 · openalex publication_date 2004/11/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this note we give a particularly short and simple proof of the following theorem of Karrass and Solitar. Let H be a finitely generated subgroup of a free group F with infinite index [F:H]. Then there is a nontrivial normal subgroup N of F such that N∩ H = \1\.