Warfield Invariants in Abelian Group Algebras
Warfield invariants in abelian group rings.
Let R be a perfect commutative unital ring without zero divisors of char(R) = p and let G be a multiplicative abelian group. Then the Warfield p-invariants of the normed unit group V (RG) are computed only in terms of R and G. These cardinal-to-ordinal functions, combined with the Ulm-Kaplansky p-invariants, completely determine the structure of V (RG) whenever G is a Warfield p-mixed group.
Weak Baer modules over graded rings
In [2], Fuchs and Viljoen introduced and classified the -modules for a valuation ring R: an R-module M is a -module if for each divisible module X and each torsion module X with bounded order. The concept of a -module was extended to the setting of a torsion theory over an associative ring in [14]. In the present paper, we use categorical methods to investigate the -modules for a group graded ring. Our most complete result (Theorem 4.10) characterizes -modules for a strongly graded ring R...
Weak dimensions and Gorenstein weak dimensions of group rings
Let be a field, and let be a group. In the present paper, we investigate when the group ring has finite weak dimension and finite Gorenstein weak dimension. We give some analogous versions of Serre’s theorem for the weak dimension and the Gorenstein weak dimension.
Wreath products in modular group algebras of some finite 2-groups.
Wreath products in the unit group of modular group algebras of 2-groups of maximal class.