Abstract: This paper obtains a necessary and sufficient condition for a quasi-left  group  to be isomorphic to a direct product of a quasi-group and a left zero band.Furthermore, a retract nil-extensions of a left group is also characterized.

Key words: direct product, quasi-groups, quasi-left groups, nil-extensions

摘要： 给出一个拟左群同构于拟群和左零带的直积的一个充分必要条件，同时给出了左群的收缩诣零扩张的一个刻画。

关键词: 直积, 拟群, 拟左群, 诣零扩张