The active-time scheduling problem considers the problem of scheduling preemptible jobs with windows (release times and deadlines) on a parallel machine that can schedule up to $g$ jobs during each timestep. The goal in the active-time problem is to minimize the number of active steps, i.e., timesteps in which at least one job is scheduled. In this way, the active time models parallel scheduling when there is a fixed cost for turning the machine on at each discrete step. This paper presents a 9/5-approximation algorithm for a special case of the active-time scheduling problem in which job windows are laminar (nested). This result improves on the previous best 2-approximation for the general case.

翻译：主动时间排期问题考虑到在平行机器上安排有窗口的可预设工作(释放时间和最后期限)的问题,该平行机器可在每个时段内安排最多不超过g美元的工作。主动时间问题的目标是尽量减少积极步骤的数量,即至少安排一个工作的时段。这样,当每个离散步骤都有固定费用打开机器时,主动时间模式平行安排。本文为工作窗口为 laminar(已取消)的当前时间排期问题的特殊案例提供了9/5的套套用算法,从而改进了以往一般情况下最佳的2套办法。