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Unit groups of group algebras of some small groups

Gaohua Tang, Yangjiang Wei, Yuanlin Li (2014)

Czechoslovak Mathematical Journal

Let F G be a group algebra of a group G over a field F and 𝒰 ( F G ) the unit group of F G . It is a classical question to determine the structure of the unit group of the group algebra of a finite group over a finite field. In this article, the structure of the unit group of the group algebra of the non-abelian group G with order 21 over any finite field of characteristic 3 is established. We also characterize the structure of the unit group of F A 4 over any finite field of characteristic 3 and the structure of...

Unitary subgroup of integral group rings.

Adalbert A. Bovdi, Sudarshan K. Sehgal (1992)

Publicacions Matemàtiques

Let A be a finite abelian group and G = A x 〈b〉, b2 = 1, ab = a-1, ∀a ∈ A. We find generators up to finite index of the unitary subgroup of ZG. In fact, the generators are the bicyclic units. For an arbitrary group G, let B2(ZG) denote the group generated by the bicyclic units. We classify groups G such that B2(ZG) is unitary.

Units in group rings of crystallographic groups

Karel Dekimpe (2003)

Fundamenta Mathematicae

In [3], the authors initiated a technique of using affine representations to study the groups of units of integral group rings of crystallographic groups. In this paper, we use this approach for some special classes of crystallographic groups. For a first class of groups we obtain a normal complement for the group inside the group of normalized units. For a second class of groups we show that the Zassenhaus conjectures ZC1 and ZC3 are valid. This generalizes the results known for the infinite dihedral...

Units of F5kD10

Gildea, Joe (2010)

Serdica Mathematical Journal

2000 Mathematics Subject Classification: 20C05, 16U60, 16S84, 15A33.The Structure of the Unit Group of the Group Algebra of the group D10 over any field of characteristic 5 is established in terms of split extensions of cyclic groups.

Vector invariant ideals of abelian group algebras under the actions of the unitary groups and orthogonal groups

Lingli Zeng, Jizhu Nan (2016)

Czechoslovak Mathematical Journal

Let F be a finite field of characteristic p and K a field which contains a primitive p th root of unity and char K p . Suppose that a classical group G acts on the F -vector space V . Then it can induce the actions on the vector space V V and on the group algebra K [ V V ] , respectively. In this paper we determine the structure of G -invariant ideals of the group algebra K [ V V ] , and establish the relationship between the invariant ideals of K [ V ] and the vector invariant ideals of K [ V V ] , if G is a unitary group or orthogonal group....

Warfield invariants in abelian group rings.

Peter V. Danchev (2005)

Extracta Mathematicae

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

Mark Teply, Blas Torrecillas (1998)

Colloquium Mathematicae

In [2], Fuchs and Viljoen introduced and classified the B * -modules for a valuation ring R: an R-module M is a B * -module if E x t R 1 ( M , X ) = 0 for each divisible module X and each torsion module X with bounded order. The concept of a B * -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 B * -modules for a group graded ring. Our most complete result (Theorem 4.10) characterizes B * -modules for a strongly graded ring R...

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