A simple characterization of the infinitesimal motions separating general polyhedra in contact

We present a simple local geometric characterization of the configuration space of two polyhedra in contact that provides a representation of all infinitesimal motions that separate them. The polyhedra considered are general in the sense that they possibly have non-convex faces and arbitrary number of holes. The approach presented has two main advantages over former ones: 1) it only relies on the classical basic contacts between polyhedra, i.e. the vertex-face and edge-edge contacts; and 2) it does not require the focal decomposition of non-convexities into convex parts