Fractal properties of robust strange nonchaotic attractors in maps of two or more dimensions

We consider the existence of robust strange nonchaotic attractors in a simple class of quasiperiodically forced systems. Rigorous results are presented demonstrating that the resulting attractors are strange in the sense that their box-counting dimension $D_0$ is larger than their information dimension $D_1$ by $1$ (i.e., $D_0{=D}_1+1).\mathrm{}$ We also show how this property is manifested in numerical experiments.