Control subgroups and birational extensions of graded rings.
Copure injective resolutions, flat resolvents and dimensions
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 -Gorenstein rings. As a consequence, if the full subcategory of strongly copure injective (respectively flat) modules over a left and right noetherian ring has cokernels (respectively kernels), then is -Gorenstein.
Corrigendum to the paper " Quotient rings and one-sided primes".
Costable rings
Countably thick modules
The purpose of this paper is to further the study of countably thick modules via weak injectivity. Among others, for some classes of modules in we study when direct sums of modules from satisfies a property in . In particular, we get characterization of locally countably thick modules, a generalization of locally q.f.d. modules.
CS-modules and annihilator conditions.
Cyclic extensions and crossed-products