“…• The related topic of design and stability analysis of state observers has been analysed for MDIs like FOSwP with convex and prox-regular sets [522,524] with AC or BV solutions (hence allowing for Zeno solutions), SOSwP in (4.10) [523], vibro-impact dynamics (i.e., no persistent contact phases) in [252,262,411,417,419,418]. • Finite-time stability and convergence in continuous-time and in discrete-time systems [459,458,385,547,16,146,10,255,253,423,421,422]: finite-time can be obtained by means of "plastic" impact (or accumulation of impact times), or using non-Lipschitz dynamics near the equilibrium (set-valued friction, slidingmode control). • Stability of equilibria or periodic trajectories in vibro-impact systems using impact Poincaré maps [68,380,567] [130, Section 7.3].…”