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Dynamic Traveling Repair Problem with an Arbitrary Time Window

机译:任意时间窗的动态旅行修复问题

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We consider the online Dynamic Traveling Repair Problem (DTRP) with an arbitrary size time window. In this problem we receive a sequence of requests for service at nodes in a metric space and a time window for each request. The goal is to maximize the number of requests served during their time window. The time to traverse between two points is equal to the distance. Serving a request requires unit time. Irani et al., SODA 2002 considered the special case of a fixed size time window. In contrast, we consider the general case of an arbitrary size time window. We characterize the competitive ratio for each metric space separately. The competitive ratio depends on the relation between the minimum laxity (the minimum length of a time window) and the diameter of the metric space. Specifically, there exists a constant competitive algorithm only when the laxity is largeT than the diameter. In addition, we characterize the rate of convergence of the competitive ratio, which approaches 1, as the laxity increases. Specifically, we provide matching lower and upper bounds. These bounds depend on the ratio between the laxity and the optimal TSP solution of the metric space (the minimum distance to traverse all nodes). An application of our result improves the previously known lower bound for colored packets with transition costs and matches the known upper bound. In proving our lower bounds we use an embedding with some special properties.
机译:我们考虑具有任意大小时间窗口的在线动态旅行维修问题(DTRP)。在这个问题中,我们在度量空间中的节点处接收到一系列服务请求,并为每个请求提供了一个时间窗口。目标是在其时间窗口内最大化服务请求的数量。在两点之间移动的时间等于距离。服务请求需要单位时间。 Irani等人在SODA 2002中考虑了固定大小的时间窗口的特殊情况。相反,我们考虑任意大小的时间窗口的一般情况。我们分别描述每个度量空间的竞争比率。竞争比率取决于最小松弛度(时间窗口的最小长度)与度量空间直径之间的关系。具体地,仅当松弛度大于直径T时,才存在恒定竞争算法。此外,随着松驰度的增加,我们描述了竞争比率的收敛速度,趋近于1。具体来说,我们提供匹配的上下限。这些界限取决于松弛度与度量空间的最佳TSP解决方案之间的比率(遍历所有节点的最小距离)。我们的结果的应用改善了具有过渡成本的彩色数据包的先前已知的下限,并匹配了已知的上限。在证明下界时,我们使用具有某些特殊属性的嵌入。

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