Erratum to: “Elementary embeddings in torsion-free hyperbolic groups”

Abstract

The notations adopted are those of [Per11]. Proposition 5.11 of [Per11] states that if a torsion-free hyperbolic group A admits a cyclic JSJ-like decomposition Λ, and a non injective morphism f : A → A which restricts to conjugation on each non surface type vertex group, and sends surface type vertex groups to non abelian images, then there is a retraction r : A→ A′ which gives A a structure of hyperbolic floor over A′. Unfortunately, we realised that Proposition 5.11 fails to hold in a few exceptional low complexity cases. The natural modification to overcome this mistake is to proceed to a slight generalization of the notion of hyperbolic floors and hyperbolic towers, which we present in Section 1. As we will see in Section 2, however, this does not affect Theorem 1.2, the main result of the paper. Moreover, Theorem 1.2 is the only result which directly uses Proposition 5.11 in its proof. For a corrected version of the paper, see [Per09]. We sincerely apologize for any confusion caused by this mistake.