Article
Keywords:
monogeny class; epigeny class; weak Krull-Schmidt theorem; hereditary torsion theory; uniform module; co-uniform module
Summary:
Recently, A. Facchini [3] showed that the classical Krull-Schmidt theorem fails for serial modules of finite Goldie dimension and he proved a weak version of this theorem within this class. In this remark we shall build this theory axiomatically and then we apply the results obtained to a class of some modules that are torsionfree with respect to a given hereditary torsion theory. As a special case we obtain that the weak Krull-Schmidt theorem holds for the class of modules that are both uniform and co-uniform. A simple example shows that this generalizes the result of [3] mentioned above.
References:
                        
[1] Bican L., Kepka T., Němec P.: 
Rings, Modules and Preradicals. Marcel Dekker New York, Longman Scientific Publishing, London (1982). 
MR 0655412[2] Bican L., Torrecillas B.: 
QTAG torsionfree modules. Comment. Math. Univ. Carolinae 33 (1994), 1-20. 
MR 1173740[3] Facchini A.: 
Krull-Schmidt fails for serial modules. Trans. Amer. Math. Soc. 348 (1996), 4561-4575. 
MR 1376546 | 
Zbl 0868.16003[4] Golan J.S.: 
Torsion Theories. Pitman Monographs and Surveys in Pure and Appl. Math. Longman Scientific Publishing, London (1986). 
MR 0880019 | 
Zbl 0657.16017[5] Herbera D., Shamsuddin A.: 
Modules with semi-local endomorphism rings. Proc. Amer. Math. Soc. 123 (1995), 3593-3600. 
MR 1277114[6] Stenström B.: 
Rings of Quotients. Springer Berlin (1975). 
MR 0389953[8] Facchini A.: 
Module Theory. Endomorphism rings and direct decompositions in some classes of modules (Lecture Notes). to appear. 
MR 1634015