So it has been an open problem and the front of Operational Research and Combinatorial Optimization.
车辆优化调度问题已经成为运筹学与组合优化领域的前沿与研究热点问题。
Timetable problem is a typical problem of combined optimization in the fields of operational research and systems engineering, which belongs to NP problem.
时间表问题是运筹学领域和系统工程领域中的典型组合优化问题，是由于事件对时间和空间的资源争夺而产生的，属于NP完全类问题。
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