中文摘要：

证明了如果所有循环序S-系都是平坦的，则S是序正则的幺半群，并构造了一个序半群说明其逆不成立，从而利用范畴给出了序正则半群的一个充分条件。并把S-系中关于循环S-系的部分结果推广到序S-系中，同时部分地回答了Bulman-Fleming等人提出的公开问题。

英文摘要：

A necessary condition that all cyclic S- posets are flat was given. The condition is not sufficient which is illustrated by an example. The results on Sacts can be also obtained as applications of the results of this paper. The question raised by Bulman-Fleming et al was answered partly.