S－系的稳定扭类

STABLE TORSION GLASSES OF S-SYSTEMS

首先证明了Ｓ－系及其同态的正合列的一些结果。利用Ｓ－系的正合列，研究了Ｓ－系的关于取内射包闭的一类扭论，即稳定扭论。证明了一个（特殊）扭论τ是稳定的，当且仅当对任意的（τ－）内射Ｓ－系Ｍ，其扭根Ｔ＿τ（Ｍ）是Ｍ的直积因子。

In this paper we proved some results of exact sequences of S- systems.A torsiontheory is called a stable torsion theory if its torsion class is closed under taking injectivehulls.We proved that a hereditary(special)torsion theory τis stable if and only if for each(τ-injective)S-system M,the τ-torsion radical T_τ(M)is a direct summand of M.