Combinatorial mapping-tori, branched surfaces and free group automorphisms
Résumé
We give a characterization of the geometric automorphisms in a certain class of (not necessarily irreducible) free group automorphisms. When the automorphism is geometric, then it is induced by a pseudo-Anosov homeomorphism without interior singularities. An outer free group automorphism is given by a 1-cocycle of a 2-complex (a standard dynamical branched surface) the fundamental group of which is the mapping-torus group of the automorphism. A combinatorial construction elucidates the link between this new representation and the classical representation of a free group automorphism by a graph-map.
Domaines
Théorie des groupes [math.GR]
Origine : Fichiers produits par l'(les) auteur(s)
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