摘要: 讨论了Casten的NpNn系统学、壳模型的配对近似方法应用及多体系统的某些固有性质，主要侧重于这3个问题研究的物理基础和意义。I would like to discuss low-lying systematics of NnNp suggested by Rick Casten, Nucleon-pair approximation of the nuclear shell model and its applications, and intrinsic properties of many-body systems in the presence of random interactions. I shall emphasize on backgrounds and perspectives of these problems, and summarize our basic understanding on these problems, after many efforts made by my collaborators and me.