Michael Field, Ian Melbourne and Matthew Nicol.

Symmetric attractors for diffeomorphisms and flows



Let G be a finite group of orthogonal transformations acting on n-dimensional Euclidean space. In this work we describe the possible symmetry groups that can occur for attractors of smooth (invertible) G-equivariant dynamical systems. (For continuous non-invertible systems, see P. Ashwin and I. Melbourne. Symmetry groups of attractors. Arch. Rat. Mech. Anal. 126 (1994) 59-78.) In case G contains no reflections, and n is at least 3, our results imply there are no restrictions on symmmetry groups. In case n is at least 4 (diffeomorphisms) or 5 (flows), we show that we may construct attractors which are Axiom A. We also give a complete description of what can happen in low dimensions.