Mathematical physics provides an exact, quantitative account of motion which has enabled us to send spacecraft to distant planets and to aim our missiles with deadly accuracy. It becomes unwieldy, perhaps even impotent, when dealing with less tidy situations such as the flow of traffic through the streets of a city, the movement of people about an office, or the procession of weather systems around the globe. The degree of idealization required even to describe these phenomena in mathematical terms inevitably leaves out many factors which are in fact instrumental in determining how they happen. In our everyday life, too, our predictive abilities are sorely limited, yet we have evolved a workable, and in some respects quite refined network of commonsense notions which enable us to get by most of the time. In disciplines such as philosophy and artificial intelligence (Davis, 1990; Hobbs and Moore, 1985) there is an intense interest in laying bare and systematising the conceptual schemes underlying our everyday competence in handling such notions as time, space, and movement, and this chapter is intended to contribute to that enterprise.
KeywordsDiscrete Time Discrete Space Proper Part Dense Time Pair Model
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