Control with limited information

A long-standing open conceptual problem has been the following: How does "i nformation" interact with control of a system, in particular feedback contr ol, and what is the value of "information" in achieving performance objecti ves for the system through the exercise of control? In answering this quest ion we haw to remember that in contrast to a variety of communication setti ngs, the issue of time-delay is of primary importance for control problems, especially control of systems which are unstable. We discuss various issue s arising from these fundamental questions.