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Quadratic properties in group amalgams

  • Benjamin Fine EMAIL logo , Aila Rosenberger and Gerhard Rosenberger
Published/Copyright: August 29, 2011
Journal of Group Theory
From the journal Volume 14 Issue 5

Abstract

Lyndon in [Combinatorial Group Theory, Springer-Verlag, 1977] proved that in a free group F each solution set {x, y, z} of the quadratic equation x2y2z2 = 1 generates a cyclic group. This theorem launched the whole theory of equations over free groups which led eventually to the solution of the Tarski conjectures. Since Lyndon's theorem can be phrased as a universal sentence, it is true in all fully residually free groups, if we replace cyclic by abelian. In the present paper we consider amalgams of groups which satisfy Lyndon's theorem. We prove that this property and several other related properties involving quadratic and quadratic-type equations are preserved under free products with malnormal amalgamated subgroups. The situation in HNN groups is more complicated.

Received: 2009-07-02
Revised: 2010-08-27
Published Online: 2011-08-29
Published in Print: 2011-September

© de Gruyter 2011

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