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作 者:陈彦光[1]
出 处:《陕西师范大学学报(自然科学版)》2001年第2期98-102,共5页Journal of Shaanxi Normal University:Natural Science Edition
基 金:国家自然科学基金!资助项目 ( 4 97710 32 ) ;河南省自然科学基础研究资助!项目 ( 0 0 4 0 712 0 0 )
摘 要:周一星在研究京津冀地区的城市规模分布时发现Zipf模型P(r) =P1r-q的参数P1的计算值与实际值存在误差 ,即最大城市的人口数的理论值与实际数有不容忽视的差距 ,从而出现了理论与实验的矛盾 .为了解决这一问题 ,从一对具有普遍意义的奇异对称序列出发 ,导出了城市位序 规模法则的精确表达式 ,从而揭示了“周一星难题”的数理本质 .It was found by Y.X. Zhou(1995) in his studying the city-size distribution of the Beijing area, the Tianjin area, and Hebei Province in North China that there is a great difference between the calculated value of the parameter, P 1, in Zipfs model, P(r)=P 1r -q , and the real population value of the first-ranking city in a region. The contradiction between theory and reality is named ‘the Zhous paradox′ by the author of this paper in which the mathematical essence of the `paradox′ is brought to light. The Zipf model is precisely derived out as follows, P(r)=C mr -q =τ qP 1r -q ,where τ=(δ-δ 1-m )/(δ-1), and q>0,δ>1,m=1,2,…,N. When and only when τ q=1,C m=τ qP 1=P 1, however, it is obvious that τ q≥1, so C m≥P 1, and moreover, C m is not a constant in a strict sense. Because C m used to be considered to be equal to P 1, a paradox emerged. The solution to the problem is to substitute a three-parameter model, P(r)=C(r-α) -dz , for the traditional two-parameter Zipf′s model, where C, α, and dz are parameters. It can be proved that dz=q=1/D, and D is a kind of fractal dimension.
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