In this paper we study the existence of FIn-envelopes, FI1/n-envelopes and FIn-covers, where FIn denotes the class of all n-absolute pure modules for an integer n 〉 0 or n = ∞. We prove that FI1/n-envelopes and FIn-...In this paper we study the existence of FIn-envelopes, FI1/n-envelopes and FIn-covers, where FIn denotes the class of all n-absolute pure modules for an integer n 〉 0 or n = ∞. We prove that FI1/n-envelopes and FIn-covers exist over an n-coherent ring R, and FIn-covers and special FIn-preenvelopes exist over any ring R.展开更多
文摘In this paper we study the existence of FIn-envelopes, FI1/n-envelopes and FIn-covers, where FIn denotes the class of all n-absolute pure modules for an integer n 〉 0 or n = ∞. We prove that FI1/n-envelopes and FIn-covers exist over an n-coherent ring R, and FIn-covers and special FIn-preenvelopes exist over any ring R.
基金Supported by the National Basic Research Programof China(973 Program)(No.2001CB309300),the NNSF of China (No.10425524 and No.10574125),and the European Commission under Contact(No.007065)(Marie Curie Action).
