Long turns, INP's and index for free group automorphisms

Thierry Coulbois (1) , Martin Lustig (1)

1 I2M - Institut de Mathématiques de Marseille

The goal of this paper is to introduce a new tool, called {\em long turns}, which is a useful addition to the train track technology for automorphisms of free groups, in that it allows one to control periodic INPs in a train track map and hence the index of the induced automorphism.

Mots clés: free group automorphisms; train tracks; Nielsen path; index

Domaines: Théorie des groupes [math.GR]

Thierry Coulbois, Martin Lustig. Long turns, INP's and index for free group automorphisms. 2015. ⟨hal-01318378⟩