ON ALMOST PRECOVERS AND ALMOST PREENVELOPES  

作　　者：毛立新 丁南庆 佟文廷 

机构地区：[1]Department of Basic Courses Nanjing Institute of Technology,Nanjing 211167,China [2]Department of Mathematics Nanjing University,Nanjing 210093,China

出　　处：《Acta Mathematica Scientia》2006年第3期395-400,共6页数学物理学报（B辑英文版）

基　　金：This research was partially supported by the Specialized Research Fund for the Doctoral Program of Higher ducation of China (20020284009, 20030284033) NSF of China (10331030) Jiangsu Planned Projects for Postdoctoral Research Funds (0203003403)the Postdoctoral Research Funds of China (2006037713)and the Nanjing Institute of Technology of China.

摘　　要：Let C be a class of R-modules closed under isomorphisms and finite direct sums. It is first shown that the finite direct sum of almost C-precovers is an almost C-precover and the direct sum of an almost C-cover and a weak C-cover is a weak C-cover. Then the notion of almost C-preenvelopes is introduced and studied.Let C be a class of R-modules closed under isomorphisms and finite direct sums. It is first shown that the finite direct sum of almost C-precovers is an almost C-precover and the direct sum of an almost C-cover and a weak C-cover is a weak C-cover. Then the notion of almost C-preenvelopes is introduced and studied.

关 键 词：Almost precover almost preenvelope 

分 类 号：O153.3[理学—数学]