On lifting modules

 

作者: Derya Keskin,  

 

期刊: Communications in Algebra  (Taylor Available online 2000)
卷期: Volume 28, issue 7  

页码: 3427-3440

 

ISSN:0092-7872

 

年代: 2000

 

DOI:10.1080/00927870008827034

 

出版商: Gordon and Breach Science Publishers Ltd.

 

数据来源: Taylor

 

摘要:

LetRbe a ring with identity and letbe a finite direct sum of relatively protectiveR-modulesMiThen it is proved thatMis lifting if and only ifMis amply supplemented andMiis lifting for all 1 ≤i≤n.Letbe a finite direct sum ofR-modulesMi. We prove thatMis (quasi-) discrete if and only ifare relatively projective (quasi-) discrete modules. We also prove that, for an amply supplementedR-moduleM=M1⊕M2such thatM1andM2have the finite exchange propertyMis lifting if and only ifM1andM2are lifting and relatively small projectiveR-modules and every co-closed submoduleNofMwithM=N+M1=N+M2is a direct summand ofM.Finally, we prove that, for a ringRsuch that every direct sum of a liftingR-module and a simpleR-module is lifting, every simpleR-module is smallM-projective for any liftingR-moduleM.

 

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