Studying the structure of the K_2 -group is one of the basic works of algebraic K -theory. Especially to study the structure of the K_2 -group of O_F of algebraic number field F is a very important work, where O_F is the ringof integers of F.

• 对K_2群的结构的研究是代数K-理论的基本任务之一,特别是对代数数域F的代数整数环O_F的K_2群的结构的研究,是一个非常关键并且具有重要意义的问题。