• 　　实施一个工程计划时，若将整个工程分成若干个工序，有些工序可以同时实施，有些工序必须在完成另一些工序之后才能实施，工序之间的次序关系可用有向图表示。一个工程的完成时间可分为：最早完成时间和最晚完成时间。

• 　　关键路径的算法主要是通过计算工程的各个工序的缓冲时间（即：最晚完成时间减去最早完成时间的差），若某些工序的缓冲时间为零，这些工序即为关键路径，而缓冲时间不为零的工序就不是关键路径。

-•　Implement a project plan, if the entire project is divided into several steps, some steps can be implemented simultaneously, some process must be completed before the implementation of some other process, process an order relation between the directed graph representation available. A project completion time can be divided into: earliest completion time and the latest finish time. •　Critical path algorithm works mainly through the various steps of calculating buffer time (namely: the latest finish time minus the earliest completion time difference), if certain processes buffering time is zero, these processes is the critical path, and buffer time is not zero step is not critical path.