76 research outputs found
Isomorphism of Commutative Group Algebras over all Fields
It is argued that the commutative group algebra over
each field determines up to an isomorphism its group basis for
any of the following group classes:
• Direct sums of cocyclic groups
• Splitting countable modulo torsion groups whose torsion parts
are direct sums of cyclics;
• Splitting groups whose torsion parts are separable countable
• Groups whose torsion parts are algebraically compact
• Algebraically compact groups
These give a partial positive answer to the R.Brauer’s classical
problem
Rings with Jacobson units
We introduce and study the notion of JU rings, that are, rings having only Jacobson units. In parallel to the so-called UU rings, these rings also form a large class and have many interesting properties established in the present paper. For instance, it is proved that any exchange JU ring is semi-boolean, and vice versa. This somewhat extends a result due to Lee-Zhou (Glasg. Math. J., 2008) and Danchev-Lam (Publ. Math. Debrecen, 2016)
On exchange π-UU unital rings
We prove that a ring R is exchange 2-UU if, and only if, J(R) is nil and R/J(R)≅B×C, where B is a Boolean ring and C is a ring with C ⊆ Πμ ℤ₃ for some ordinal μ. We thus somewhat improve on a result due to Abdolyousefi-Chen (J. Algebra Appl., 2018) by showing that it is a simple consequence of already well-known results of Danchev-Lam (Publ. Math. Debrecen, 2016) and Danchev (Commun. Korean Math. Soc., 2017)
Basic subgroups in abelian group rings
summary:Suppose is a commutative ring with identity of prime characteristic and is an arbitrary abelian -group. In the present paper, a basic subgroup and a lower basic subgroup of the -component and of the factor-group of the unit group in the modular group algebra are established, in the case when is weakly perfect. Moreover, a lower basic subgroup and a basic subgroup of the normed -component and of the quotient group are given when is perfect and is arbitrary whose is -divisible. These results extend and generalize a result due to Nachev (1996) published in Houston J. Math., when the ring is perfect and is -primary. Some other applications in this direction are also obtained for the direct factor problem and for a kind of an arbitrary basic subgroup
Warfield Invariants of
Let be a commutativeunitary ring of prime characteristic and let be an Abelian group. We calculateonly in terms of and (and their sections)Warfield -invariants of thequotient group , that is, the group of all normalized units in the groupring modulo . This supplies recent results of ours in (Extr. Math., 2005),(Collect. Math., 2008) and (J. Algebra Appl., 2008)
Invo-regular unital rings
It was asked by Nicholson (Comm. Algebra, 1999) whether or not unit-regular rings are themselves strongly clean. Although they are clean as proved by Camillo-Khurana (Comm. Algebra, 2001), recently Nielsen and Ster showed in Trans. Amer. Math. Soc., 2018 that there exists a unit-regular ring which is not strongly clean. However, we define here a proper subclass of rings of the class of unit-regular rings, called invo-regular rings, and establish that they are strongly clean. Interestingly, without any concrete indications a priori, these rings are manifestly even commutative invo-clean as defined by the author in Commun. Korean Math. Soc., 2017
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