Medial Axis is known to be unstable for non smooth objects. The Medial Axis has applications in image analysis and mathematical morphology, Solid Modeling, or domain decomposition for CAD to CAE (i.e. Finite Elements) ...

In this paper, we give a very simple and purely topological condition for two surfaces to be isotopic. This work is motivated by the problem of surface approximation. Applications to implicit surfaces are given, as well ...