“…Moreover, the global existence of the hyperchaotic invariant set gives an explanation of the difficulty in most of the numerical simulations in literature to provide with a clear study of the behavior of the systems. As to obtain an analytical proof of this fact is not possible (or at least quite complex), we give some computerassisted proofs, thanks to the use of the CAPD library [36] of rigorous computing and the techniques developed in [37][38][39][40]. To that goal, we take the parameter values a = 0.27857, b = 3, c = 0.3 and d = 0.05, where we have numerically detected the coexistence of a hyperchaotic saddle and a chaotic attractor, and we define a Poincaré section This proves (see [40,Lemma 3.5]) that B is a trapping region for P , namely P (B) ⊂ B.…”