%0 Journal Article %A Lowrance, John D. and Friedman, Daniel P. %T Hendrix's Model for Simultaneous Actions and Continuous Processes: An Introduction and Implementation %B International Journal of Man-Machine Studies %P 537-581 %V 9 %D 1977 %X This paper presents a self-contained introduction and implementation description to a simulation system for modeling simultaneous action and continuous processes (Hendrix, 1973). The essence of the system is described by a portion of its abstract: ``A new methodology for the construction of world models is presented. The central feature of this methodology is a mechanism which makes possible the modeling of (1) simultaneous, interactive processes, (2) processes characterized by a continuum of gradual change, (3) involuntarily activated processes (such as the growing of grass) and (4) times as a continuous phenomena.'' and by a recent review, Gains (1975): ``This is a fascination paper that will be of interest outside the ``artificial intelligence'' (AI) context in which it is written, from those concerned with simulating and controlling multi-element systems to those interested in operational definitions of concepts such as causality.'' Three robot world models are incrementally developed, each introducing a new modeling concept. World models, including a robot world (with sample output), electrical world, and a Turing world are also presented. The interactive operating environment represented permits the user to inspect and alter the run-time structure. A detailed account of the implementation is presented.