Coordination

Abstract

Interactive computation seems like one of the oldest and most familiar aspects of computing. It was introduced in the first time-sharing systems in the late 1950s. In what way is interactive computation, as suggested by this book's title, a new paradigm? Since those early days, the theory of computation has dwelt on machines and algorithms for mathematical functions. We might call these "function machines". The theory provided us with a deep and rich understanding of algorithmic complexity and the limitations of various classes of function machines. It gave us the Church-Turing thesis, which postulates that any effective procedure can be realized as a function machine. Its treatment of interaction has been limited to concurrent systems of interacting function machines. Real systems, however, are far more than networks of function machines; they are symbiotic communities of machines and humans. Humans contribute many things that function machines cannot do, such as recognizing context, making new distinctions, and creating new abstractions. Human-machine systems routinely carry out sophisticated computational tasks that the old theory says are not computable. As computational theorists grapple with this anomaly, they are extending the theory in refreshing directions and are introducing entirely new ways to think about computation and its limits. This is the revolution the editors are celebrating in this book. Our purpose in this chapter is to present two complementary views of coordination in real human-machine systems. Coordination is the heart of interaction. Coordination is one of the six fundamental areas of computing principles. It is concerned with managing the interactions among multiple activities so that they achieve a single, collective result. Those who design, build, and evaluate interactive systems have employed coordination principles for many years. Coordination plays a similarly fundamental role in management science. Coordination principles will undoubtedly play a central role in the new theoretical paradigms. © 2006 Springer-Verlag Berlin Heidelberg.