Generalized dynamical systems

There has been active interest recently, some of it promted by the paper of Rosenbrock [1], in the structure of linear time-invariant dynamical systems at ´infinite frequencies´. We review some of this work, [2]-[10], noting recent extensions, and suggesting useful directions for future work. Of particular interest are systems that exhibit impulsive responses to initial conditions; these we have termed generalized dynamical systems.