“…The sum of absolute value of synchronization errors: jx s (t) À x m (t)j + jy s (t) À y m (t)j + jz s (t) À z m (t)j + jw s (t) À w m (t)j. is full rank because det(b, Ab, A 2 b, A 3 b) = Àd 2 c + dca + dc 2 a À c À 2c 2 À c 3 5 0, where b = (0, 0, À1, 0) T . Therefore, from the control theory of linear system [17,18], the single-input dynamic system (12) is controllable, i.e., all the eigenvalues are controllable. Thus, we can select an appropriate feedback gain vector k such that system (11) is globally asymptotically stable at zero, that is dynamical system (10) is synchronous with Rö ssler hyper-chaotic system (5).…”