A Bi‐objective Optimization Model for Designing Safe Walking Routes for School Children

This study uses a mathematical optimization approach to design safe walking routes from school to home for children. Children are thought to be safer when walking together in groups rather than alone. Thus, we assume that the risk of walking along a given road segment in a group is smaller than that of walking the same segment alone. At the same time, the walking route between school and home for each child should not deviate substantially from the shortest route. We propose a bi‐objective model that minimizes both the total risk (particularly, the total distance walked alone) and the total walking distance for all children. We present an integer programming formulation of the proposed problem and apply this formulation to two instances based on actual road networks. We obtain Pareto optimal solutions using a mathematical programming solver and analyze the characteristics of the solutions and their potential applicability to real situations. The results show that the proposed model produces much better solutions compared with the solution where each child walks along the shortest path from school to home. In some optimal solutions, only a small deviation from the shortest path results in a dramatic reduction of the risk objective.     

再论民间祭祀文化在戏剧起源史上的重要作用——对傅谨教授《中国戏剧发源于乡村祭祀仪礼说质疑》一文的回应

傅谨教授的《中国戏剧发源于祭祀仪礼说质疑》是对拙著《中国戏剧史》的批评,但也是一种明显的误读。中国戏剧学界存在着“禁忌民俗学”的传统偏见,忽视乡村祭祀戏剧的研究成果,漠视民间祭祀文化在中国戏剧起源史上的重要作用。本文剖析中国戏曲研究禁忌民俗学偏见之特色和由来,再一次阐明《中国戏剧史》提出的“宋元戏剧在从祭祀到戏曲的过渡阶段的关键作用”。在讨论戏剧的起源时,民俗学的眼光与田野调查必不可少;而讨论戏剧的发展时,社会经济史学也成为主要的理论方法,如此才能解决祭祀性戏剧和欣赏性戏剧之间的连续性问题     

The Probabilistic Minisum Flow Interception Problem: Minimizing the Expected Travel Distance until Intercept under Probabilistic Interception

We develop a variant of the flow interception problem (FIP) in which it is more desirable for travelers to be intercepted as early as possible in their trips. In addition, we consider flows being intercepted probabilistically instead of the deterministic view of coverage assumed in the FIP literature. We call the proposed model the probabilistic minisum FIP (PMFIP); it involves minimizing the sum of the expected distance that each flow travels until intercepted at a facility among placed facilities. This extension allows us to evaluate the effect of facility location under any given value of the interception probability and to apply the model to a variety of situations. We apply the proposed model to an example network by assuming a hypothetical situation in which people gather at a stadium from various nodes on the network, and receive some goods or services on the way to the stadium. We analyze optimal solutions obtained by varying the number of facilities and interception probability. It is shown that the expected travel distance until intercept is greatly reduced by means of a few optimally located facilities under a moderate interception probability.