Abstract
Let R be a left coherent ring. We first prove that a right R-module M is strongly copure flat if and only if Ext i (M, C) = 0 for all flat cotorsion right R-modules C and i ≥ 1. Then we define and investigate copure flat dimensions of left coherent rings. Finally, we give some new characterizations of n-FC rings.
ACKNOWLEDGMENTS
This research was partially supported by National Natural Science Foundation of China (No. 10771096), Natural Science Foundation of Jiangsu Province of China (No. 2008365) and Science Foundation for Young Teachers of Northeast Normal University (09QNJJ003).
Notes
Communicated by T. Albu.