A Note on Derivations of Group Rings

1995 ◽  
Vol 38 (4) ◽  
pp. 434-437 ◽  
Author(s):  
Miguel Ferrero ◽  
Antonio Giambruno ◽  
César Polcino Milies
Keyword(s):  
Group Ring ◽  
Finite Index ◽  
Semiprime Ring ◽  
Group Rings ◽  
Locally Finite

AbstractLetRGdenote the group ring of a groupGover a semiprime ringR. We prove that, if the center ofGis of finite index and some natural restrictions hold, then everyR-derivation ofRGis inner. We also give an example of a groupGwhich is both locally finite and nilpotent and such that, for every fieldF, there exists anF-derivation ofFGwhich is not inner.

Trivial Units in Group Rings

2000 ◽  
Vol 43 (1) ◽  
pp. 60-62 ◽  
Author(s):  
Daniel R. Farkas ◽  
Peter A. Linnell
Keyword(s):  
Recent Result ◽  
Group Ring ◽  
Finite Index ◽  
Integral Group Ring ◽  
Alternative Proof ◽  
Crystallographic Group ◽  
Group Rings ◽  
Integral Group ◽  
Arbitrary Group ◽  
Normalized Units

AbstractLet G be an arbitrary group and let U be a subgroup of the normalized units in ℤG. We show that if U contains G as a subgroup of finite index, then U = G. This result can be used to give an alternative proof of a recent result of Marciniak and Sehgal on units in the integral group ring of a crystallographic group.

On the structure of some Noetherian modules over group rings

2014 ◽  
Vol 24 (02) ◽  
pp. 233-249
Author(s):  
Leonid A. Kurdachenko ◽  
Javier Otal ◽  
Igor Ya. Subbotin
Keyword(s):  
Finite Field ◽  
Group Ring ◽  
Soluble Group ◽  
Dedekind Domain ◽  
Group Rings ◽  
Property A ◽  
Locally Finite ◽  
Locally Finite Field ◽  
Noetherian Modules

In this paper, we study the structure of some Noetherian modules over group rings and deduce some statements regarding the structure of the groups involved. More precisely, we consider a module A over a group ring RG with the following property: A is a Noetherian RH-module for every subgroup H, which is not contained in the centralizer CG(A). If G is some generalized soluble group and R is a locally finite field or some Dedekind domain, we describe the structure of G/CG(A).

scholarly journals Semilocal semigroup rings

1984 ◽  
Vol 25 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Jan Okniński
Keyword(s):  
Finite Index ◽  
Group Rings ◽  
Semigroup Rings ◽  
Locally Finite

Semilocal and related classes of group rings have been investigated by many authors (cf. [10]). In particular, the following results have been obtained.Theorem A[4,10]. Let K be a field and G a group.(i) If ch K = 0, then K[G] is semilocal if and only if G is finite.(ii) If ch K = p>0 and G is locally finite, then K[G] is semilocal if and only if G contains a p-subgroup of finite index.In the case of semigroup rings some stronger conditions have been studied. Munn examined the semisimple artinian situation [6]. Zelmanov showed that if K[G]is artinian then G must be finite [11].

On Group Rings

1970 ◽  
Vol 22 (2) ◽  
pp. 249-254 ◽  
Author(s):  
D. B. Coleman
Keyword(s):  
Nilpotent Group ◽  
Commutative Ring ◽  
Group Ring ◽  
Characteristic Zero ◽  
Sylow Subgroup ◽  
Jacobson Radical ◽  
Closed Field ◽  
Group Rings ◽  
Locally Finite ◽  
Image Position

Let R be a commutative ring with unity and let G be a group. The group ring RG is a free R-module having the elements of G as a basis, with multiplication induced byThe first theorem in this paper deals with idempotents in RG and improves a result of Connell. In the second section we consider the Jacobson radical of RG, and we prove a theorem about a class of algebras that includes RG when G is locally finite and R is an algebraically closed field of characteristic zero. The last theorem shows that if R is a field and G is a finite nilpotent group, then RG determines RP for every Sylow subgroup P of G, regardless of the characteristic of R.

A NOTE ON GROUP RINGS WITH TRIVIAL UNITS

2021 ◽  
pp. 1-5
Author(s):  
A. Y. M. CHIN
Keyword(s):  
Finite Group ◽  
Commutative Ring ◽  
Group Ring ◽  
Torsion Group ◽  
Locally Finite Group ◽  
Group Rings ◽  
Prime Characteristic ◽  
Locally Finite ◽  
Characteristic Two

Abstract Let R be a ring with identity of characteristic two and G a nontrivial torsion group. We show that if the units in the group ring $RG$ are all trivial, then G must be cyclic of order two or three. We also consider the case where R is a commutative ring with identity of odd prime characteristic and G is a nontrivial locally finite group. We show that in this case, if the units in $RG$ are all trivial, then G must be cyclic of order two. These results improve on a result of Herman et al. [‘Trivial units for group rings with G-adapted coefficient rings’, Canad. Math. Bull.48(1) (2005), 80–89].

Units in Integral Group Rings for Order pq

1995 ◽  
Vol 47 (1) ◽  
pp. 113-131
Author(s):  
Klaus Hoechsmann
Keyword(s):  
Abelian Group ◽  
Group Ring ◽  
Finite Index ◽  
Finite Abelian Group ◽  
Integral Group Ring ◽  
Group Rings ◽  
Integral Group ◽  
Integral Group Rings ◽  
Group Of Units ◽  
Cyclotomic Units

AbstractFor any finite abelian group A, let Ω(A) denote the group of units in the integral group ring which are mapped to cyclotomic units by every character of A. It always contains a subgroup Y(A), of finite index, for which a basis can be systematically exhibited. For A of order pq, where p and q are odd primes, we derive estimates for the index [Ω(A) : Y(A)]. In particular, we obtain conditions for its triviality.

The Periodic Radical of Group Rings and Incidence Algebras

1998 ◽  
Vol 41 (4) ◽  
pp. 481-487 ◽  
Author(s):  
M. M. Parmenter ◽  
E. Spiegel ◽  
P. N. Stewart
Keyword(s):  
Group Ring ◽  
Partially Ordered Set ◽  
Ordered Set ◽  
Sufficient Conditions ◽  
Group Rings ◽  
Locally Finite ◽  
Partially Ordered ◽  
Incidence Algebras ◽  
Finite Partially Ordered Set ◽  
Necessary And Sufficient

AbstractLet R be a ring with 1 and P(R) the periodic radical of R. We obtain necessary and sufficient conditions for P(RG) = 0 when RG is the group ring of an FC group G and R is commutative. We also obtain a complete description of when I(X, R) is the incidence algebra of a locally finite partially ordered set X and R is commutative.

A Problem of Herstein on Group Rings

1974 ◽  
Vol 17 (2) ◽  
pp. 201-202 ◽  
Author(s):  
Edward Formanek
Keyword(s):  
Group Ring ◽  
Finite Subset ◽  
Zero Divisor ◽  
Formal Proof ◽  
Left Zero ◽  
Group Rings ◽  
Locally Finite ◽  
Image Position ◽  
Finite Sum

Let F be a field of characteristic 0 and G a group such that each element of the group ring F[G] is either (right) invertible or a (left) zero divisor. Then G is locally finite.This answers a question of Herstein [1, p. 36] [2, p. 450] in the characteristic 0 case. The proof can be informally summarized as follows: Let gl,…,gn be a finite subset of G, and let1—x is not a zero divisor so it is invertible and its inverse is 1+x+x3+⋯. The fact that this series converges to an element of F[G] (a finite sum) forces the subgroup generated by g1,…,gn to be finite, proving the theorem. The formal proof is via epsilontics and takes place inside of F[G].

Nil-clean group rings

2016 ◽  
Vol 16 (07) ◽  
pp. 1750135 ◽  
Author(s):  
Serap Sahinkaya ◽  
Gaohua Tang ◽  
Yiqiang Zhou
Keyword(s):  
Abelian Group ◽  
Nilpotent Group ◽  
Group Ring ◽  
Nilpotent Element ◽  
General Situation ◽  
Group Rings ◽  
Locally Finite ◽  
Arbitrary Ring ◽  
Clean Ring ◽  
Nil Clean Ring

An element [Formula: see text] of a ring [Formula: see text] is nil-clean, if [Formula: see text], where [Formula: see text] and [Formula: see text] is a nilpotent element, and the ring [Formula: see text] is called nil-clean if each of its elements is nil-clean. In [W. Wm. McGovern, S. Raja and A. Sharp, Commutative nil clean group rings, J. Algebra Appl. 14(6) (2015) 5; Article ID: 1550094], it was proved that, for a commutative ring [Formula: see text] and an abelian group [Formula: see text], the group ring [Formula: see text] is nil-clean, iff [Formula: see text] is nil-clean and [Formula: see text] is a [Formula: see text]-group. Here, we discuss the nil-cleanness of group rings in general situation. We prove that the group ring of a locally finite [Formula: see text]-group over a nil-clean ring is nil-clean, and that the hypercenter of the group [Formula: see text] must be a [Formula: see text]-group if a group ring of [Formula: see text] is nil-clean. Consequently, the group ring of a nilpotent group over an arbitrary ring is nil-clean, iff the ring is a nil-clean ring and the group is a [Formula: see text]-group.

Groups with every subgroup ascendant-by-finite

2013 ◽  
Vol 11 (12) ◽  
Author(s):  
Sergio Camp-Mora
Keyword(s):  
Finite Group ◽  
Finite Index ◽  
Locally Finite Group ◽  
Locally Finite ◽  
Locally Nilpotent

AbstractA subgroup H of a group G is called ascendant-by-finite in G if there exists a subgroup K of H such that K is ascendant in G and the index of K in H is finite. It is proved that a locally finite group with every subgroup ascendant-by-finite is locally nilpotent-by-finite. As a consequence, it is shown that the Gruenberg radical has finite index in the whole group.

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