Monotone periodic orbits for torus homeomorphisms

Let f be a homeomorphism of the torus isotopic to the identity and suppose that there exists a periodic orbit with a non-zero rotation vector (p/q,r/q), then f has a topologically monotone periodic orbit with the same rotation vector.Comment: 10 pages, 1 figur

Simple braids for surface homeomorphisms

Let S be a compact, oriented surface with negative Euler characteristic and let f be a homeomorphism of S that is isotopic to the identity. If there exists a periodic orbit with a non-zero rotation vector, then there exists a simple braid with the same rotation vector.Comment: 12 pages, 2 figure

On 3-manifolds that support partially hyperbolic diffeomorphisms

Let M be a closed 3-manifold that supports a partially hyperbolic diffeomorphism f. If $\pi_1(M)$ is nilpotent, the induced action of f on $H_1(M, R)$ is partially hyperbolic. If $\pi_1(M)$ is almost nilpotent or if $\pi_1(M)$ has subexponential growth, M is finitely covered by a circle bundle over the torus. If $\pi_1(M)$ is almost solvable, M is finitely covered by a torus bundle over the circle. Furthermore, there exist infinitely many hyperbolic 3-manifolds that do not support dynamically coherent partially hyperbolic diffeomorphisms; this list includes the Weeks manifold. If f is a strong partially hyperbolic diffeomorphism on a closed 3-manifold M and if $\pi_1(M)$ is nilpotent, then the lifts of the stable and unstable foliations are quasi-isometric in the universal of M. It then follows that f is dynamically coherent. We also provide a sufficient condition for dynamical coherence in any dimension. If f is center bunched and if the center-stable and center-unstable distributions are Lipschitz, then the partially hyperbolic diffeomorphism f must be dynamically coherent.Comment: 21 page

Actions of SL(n,Z) on homology spheres

Any continuous action of SL(n,Z), where n > 2, on a r-dimensional mod 2 homology sphere factors through a finite group action if r < n - 1. In particular, any continuous action of SL(n+2,Z) on the n-dimensional sphere factors through a finite group action.Comment: 11 page

Zero entropy subgroups of mapping class groups

Let $M$ be a compact surface with boundary. We are interested in the question of how a group action on $M$ permutes a finite invariant set $X \subset int(M)$. More precisely, how the algebraic properties of the induced group of permutations of a finite invariant set affects the dynamical properties of the group. Our main result shows that in many circumstances if the induced permutation group is not solvable then among the homeomorphisms in the group there must be one with a pseudo-Anosov component. We formulate this in terms of the mapping class group relative to the finite set and show the stronger result that in many circumstances (e.g. if $\partial M \ne \emptyset$) this mapping class group is itself solvable if it has no elements with pseudo-Anosov components