Hedgehogs and pseudo-foliations of surface homeomorphisms without periodic points
Alejandro Kocsard (IMPA)

The dynamics of circle homeomorphisms without periodic orbits can be rather easily described: such a map ha an irrational rotation number, admits a unique minimal set and is a topological extension of the corresponding irrational rotation. In dimension 2, the torus is the only connected orientable compact manifold admitting periodic point free homeomorphisms, but the dynamical description of these systems is much more complicated. In this talk we shall discuss the rotation theory of these maps paying especially attention to minimal homeomorphisms. We will also introduce two families of topological objects, hedgehogs and pseudo-foliations, that play a fundamental role in these works.