TAILIEUCHUNG - Mechanical Computation: its Computational Complexity and Technologies Chapter, Encyclopedia of Complexity and Systems Science

Wittman (1941) developed a prognosis scale for predicting outcome of electroshock therapy in schizophrenia, which consisted of 30 variables rated from social history and psychiatric examination. The predictors ranged from semi-objective matters (such as duration of psychosis) to highly interpretive judgments (such as anal-erotic vs. oral-erotic character). None of the predictor variables was psychometric. Numerical weights were not based on the sample statistics but were assigned judgmentally on the basis of the frequency and relative importance ascribed to them in previous studies. We may therefore presume that the weights used here were not optimal, but with 30 variables that. | Mechanical Computation its Computational Complexity and Technologies Chapter Encyclopedia of Complexity and Systems Science John H. Reif1 Article Outline Glossary I. Definition of the Subject and Its Importance II. Introduction to Computational Complexity III. Computational Complexity of Mechanical Devices and their Movement Problems IV. Concrete Mechanical Computing Devices V. Future Directions VI. Bibliography Glossary Mechanism a machine or part of a machine that performs a particular task computation the use of a computer for calculation. Computable Capable of being worked out by calculation especially using a computer. The term simulation will be both used to denote the modeling of a physical system by a computer as well as the modeling of the operation of a computer by a mechanical system the difference will be clear from the context. 1 Department of Computer Science Duke University Box 90129 Durham NC 27708-90129 USA. E-mail reif@. This work has been supported by NSF grants CCF-0432038 and CCF-0523555. I. Definition of the Subject and Its Importance Mechanical devices for computation appear to be largely displaced by the widespread use of microprocessor-based computers that are pervading almost all aspects of our lives. Nevertheless mechanical devices for computation are of interest for at least three reasons a Historical The use of mechanical devices for computation is of central importance in the historical study of technologies with a history dating to thousands of years and with surprising applications even in relatively recent times. b Technical Practical The use of mechanical devices for computation persists and has not yet been completely displaced by widespread use of microprocessor-based computers. Mechanical computers have found applications in various emerging technologies at the micro-scale that combine mechanical functions with computational and control functions not feasible by purely electronic processing. Mechanical computers also

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