On Stable and Unstable Behaviours of Certain Rotation Segments

Abstract

In this paper, we study non-wandering homeomorphisms of the two torus in the identity homotopy class, whose rotation sets are non-trivial line segments from $(0,0)$ to some totally irrational vector $(\alpha ,\beta )$. We show this rotation set is in fact a non-generic phenomenon for any $C^r$ diffeomorphisms, with $r\ge 1$. When such a rotation set does happen, assuming several natural conditions that are generically satisfied in the area-preserving world, we give a clearer description of its rotational behavior. More precisely, the dynamics admits bounded deviation along the direction $-(\alpha ,\beta )$ in the lift, and the rotation set is locked inside an arbitrarily small cone with respect to small $C^0$-perturbations of the dynamics. On the other hand, for any non-wandering homeomorphism $f$ with this kind of rotation set, we also present a perturbation scheme in order for the rotation set to be eaten by rotation sets of nearby dynamics, in the sense that the later set has non-empty interior and contains the former one. These two flavors interplay and share the common goal of understanding the stability/instability properties of this kind of rotation set.

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References in corpus (5)

• Forcing theory for transverse trajectories of surface homeomorphisms
• Uniform bounds for diffeomorphisms of the torus and a conjecture of P. Boyland
• Local Rigidity of Diophantine translations in higher dimensional tori
• Stability of the rotation set of area-preserving toral homeomorphisms
• Instability for the rotation set of diffeomorphisms of the torus homotopic to the identity