Heterodimensional cycles and noninvertible blenders in piecewise smooth two dimensional maps
Heterodimensional cycles are heteroclinic cycles that connect periodic orbits whose unstable manifolds have different dimensions. This is a source of nonhyperbolic dynamics and unstable dimension variability. For smooth invertible maps persistence of heterodimensional cycles with changing parameters is established using blenders, and this is only possible for systems of dimension three or higher. Using the idea of a snapback repeller we show that the definitions and results extend to noninvertible maps and that blender-type dynamics is possible in two dimensional piecewise smooth noninvertible maps. These piecewise smooth maps have the additional property of robust chaos, which simplifies some steps of the argument. The ideas are illustrated using a class of continuous piecewise smooth maps related to the border collision normal form.