In this paper, we show the existence of copure injective preenvelopes over noetherian rings and copure flat preenvelopes over commutative artinian rings. We use this to characterize $n$-Gorenstein rings. As a consequence, if the full subcategory of strongly copure injective (respectively flat) modules over a left and right noetherian ring $R$ has cokernels (respectively kernels), then $R$ is $2$-Gorenstein.
@article{118572, author = {Edgar E. Enochs and Jenda M. G. Overtoun}, title = {Copure injective resolutions, flat resolvents and dimensions}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {34}, year = {1993}, pages = {203-211}, zbl = {0780.18006}, mrnumber = {1241728}, language = {en}, url = {http://dml.mathdoc.fr/item/118572} }
Enochs, Edgar E.; Overtoun, Jenda M. G. Copure injective resolutions, flat resolvents and dimensions. Commentationes Mathematicae Universitatis Carolinae, Tome 34 (1993) pp. 203-211. http://gdmltest.u-ga.fr/item/118572/
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