本文以犯罪期望效用和成功概率为空间变量,用数学动态规划方法建立模型模拟罪犯在城市内选择犯罪区位的一般规律。模拟结果显示:罪犯在其犯罪规划期间内依据每次犯罪的期望收益和成功的概率来优化选择犯罪区位。罪犯总是在其感觉成功概率最高但期望效用较低的地区实施第一次犯罪,而其规划期间内的最后一次犯罪则发生在期望效用最高但成功概率较低的地区。如果一个地区的犯罪期望效用和成功的概率均较高,罪犯将集中在这一地区作案。模型所揭示的犯罪行为规律为城市犯罪的空间防范提供了有益的启示,即制定犯罪防治措施应因地制宜,在较贫穷的居住区或少年犯罪区应采取区域巡逻一类的“覆盖式”的防范措施;在较富裕或职业罪犯出没的地区应采取较复杂、严密和先进的技术防范措施。

With the method of dynamic programming,two spatial variables,the expected utility and the Probability of success for each offense,are used to model the criminal's lacation choices in urban areas.The modeling results show that a eriminal optimizes his crime location according to the expeeted utility and the probability of success during his crime planned period.A criminal usually commits his first offence in the district which has the highest probability of success but a lower expected utllity,and commits his last offence in the district where the expected utility is the highest and the success probability is lower.If a loeation has both a higher expeeted utility and a higher probability of success,the criminal will commit all his offeese in this place.The model also suggests that crime prevention measures should be adopted in the light of loeal conditons."Coering" measures,such as patolling,should be taken in the poor residential districts or delinquency districts,while more sophisticated and advanced measures should be introduced in the richer districts or the districts where career crimimals haunt.