说明：  针对操作系统中进程撤销相关理论进行实验。要求实验者设计一个程序，该程序可模拟撤销多个进程及其子孙进程。 1) 采用动态或静态方法生成一颗进程树（进程数目≥20）； 2) 设计进程撤销算法； 3) 实现进程撤销函数，采用级联方式撤销； 4) 可动态撤销进程； 5) 可动态观察进程树的情况； 6) 测试程序并得到正确结果。
(The process for revocation of the operating system in the theory of the experiment. Asked the experimenter to design a program that can simulate the process of revocation of multiple processes and their descendants. 1) generated by dynamic or static methods of a process tree (process number ≥ 20) 2) revocation of algorithm design process 3) function to achieve the process of revocation, revocation with cascade 4) The revocation process can be dynamic 5) can be dynamically observe the process of tree 6) test program and get the correct results.)