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An axiomatic approach to distance is developed which focuses on those behavioral concepts of distance related to movement in space. In particular, spatial movement by behaving units is postulated to involve a choice from among some set of abstract trips in space, and implicitly, to involve the minimization of some relevant notion of trip costs. In this context, the relevant behavioral notion of distance in space is taken to be the minimum-cost distance generated by this choice process. These trip-cost concepts extend the classical notions of paths, path lengths, and shortest paths in metric spaces. Hence many of the analytical results of the paper involve extensions of classical shortest-path distance properties to minimum-cost distances. In addition to these extensions, a characterization theorem is given which specifies the possible functional relationships between trip costs and their associated path lengths. These relationships include most functional forms which are commonly employed in the literature. 相似文献
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Riddell JB 《Progress in human geography》1989,13(2):267-276
Progress in development geography has been recently associated with the shift of the perspective on underdevelopment from a right-wing, conservative standpoint to a leftward, liberal-radical position. Marxism often conceals its message in obscure rhetoric with moral overtones on colonialism, slavery, poverty, and underdevelopment. Liberal academics have lamely acceded to the dogmas of this once-assertive ideology. Marxist view have exerted a stimulus on debates, but could not provide answers to the issues of this discipline. The hopes of development and prosperity a generation ago have evaporated only to be replaced by news of economic malaise, the food crisis, and crushing debt. In the late 1980's geographers addressed Third World environmental issues. Blaikie and Brookfield examined environmental deterioration among elements of the population-environment issue. Lewis and Berry dealt with African environments and resources. Watts and Bassett touched on agrarian and political concerns in West Africa. Adams examined water resources development in Nigeria's Sokoto Valley. Bryceson analyzed the political economy of agriculture in Tanzania. Lawson depicted how government policy bore on agriculture and its regional pattern. Crush detailed the absorption of Swazi labor into the South African economy. Dayal described the deficiency diet of agricultural workers in Bangladesh. Others examined Africa's financial disaster, Japan's trade surplus, and the global population crisis. Nevertheless, the dearth of output on and neglect of Third World issues by human geographers awaits positive research publications. 相似文献
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