Laminations, trees, and irreducible automorphisms of free groups.

Mladen Bestvina, Mark Feighn and Michael Handel

Abstract. We examine the action of Out(F_n) on the set of (irreducible) 
laminations. Consequences include a special case of the Tits alternative for 
Out(F_n), the discreteness of certain naturally arising group actions on trees,
and word hyperbolicity of certain semidirect products.