Scanning the issues

During the 1960s, system theory was dominated by an interior point of view, conceptualized by a state and state-variable methodology. Since 1970, however, the exterior point of view ¿ embodied by operator theoretic techniques ¿ has emerged as a viable contender in the area, a distinction that is inescapable when reading through the special issue on system theory that the Proceedings of the IEEE has prepared for January 1976.