arXiv subjects
Publications and source records attributed to Inder Bir S. Passi.
The augmentation powers in an integral group ring $\mathbb ZG$ induce a natural filtration of the unit group of $\mathbb ZG$ analogous to the filtration of the group $G$ given by its dimension series $\{D_n(G)\}_{n\ge 1}$. The purpose of the present article is to investigate this filtration, in particular, the triviality of its intersection.
The paper develops further the theory of quandle rings which was introduced by the authors in a recent work. Orderability of quandles is defined and many interesting examples of orderable quandles are given. It is proved that quandle rings of left or right orderable quandles which are semi-latin have no zero-divisors. Idempotents in quandle rings of certain interesting quandles are computed and used to determine sets of maximal quandles in these rings. Understanding of idempotents is further applied to determine automorphism groups of these quandle rings. Also, commutator width of quandle rings is introduced and computed in a few cases. The paper conclude by commenting on relation of quandle rings with other well-known non-associative algebras.
The object of this paper is to study (infinite) groups whose integral group rings have only trivial central units. This property is closely related to a property, here called the RS-property (\cite{DMS05}, \cite{RS90}), involving conjugacy in the group.
This paper presents a description of the fourth dimension quotient, using the theory of limits of functors from the category of free presentations of a given group to the category of abelian groups. A functorial description of a quotient of the third Fox subgroup is given and, as a consequence, an identification (not involving an isolator) of the third Fox subgroup is obtained. It is shown that the limit over the category of free representations of the third Fox quotient represents the composite of two derived quadratic functors.
This paper is about application of various homological methods to classical problems in the theory of group rings. It is shown that the third homology of groups plays a key role in Narain Gupta's three normal subgroup problem. For a free group $F$ and its normal subgroups $R,\,S,\,T,$ and the corresponding ideals in the integral group ring $\mathbb Z[F]$, ${\bf r}=(R-1)\mathbb Z[F],\ {\bf s}=(S-1)\mathbb Z[F],\ {\bf t}=(T-1)\mathbb Z[F],$ a complete description of the normal subgroup $F\cap (1+{\bf rst})$ is given, provided $R\subseteq T$ and the third and the fourth homology groups of $R/R\cap S$ are torsion groups.
The object of study in this paper is the finite groups whose integral group rings have only trivial central units. Prime-power groups and metacyclic groups with this property are characterized. Metacyclic groups are classified according to the central height of the unit groups of their integral group rings.
An approach to identify the normal subgroups determined by ideals in free group rings with the help of the derived functors of non-additive functors is explored. A similar approach, i.e., via derived functors, for computing limits of functors from the category of free presentations to the category of abelian groups, arising from commutator structure of free groups, is also discussed.
For a Lie ring $L$ over the ring of integers, we compare its lower central series $\{γ_n(L)\}_{n\geq 1}$ and its dimension series $\{δ_n(L)\}_{n\geq 1}$ defined by setting $δ_n(L)= L\cap \varpi^n(L)$, where $\varpi(L)$ is the augmentation ideal of the universal enveloping algebra of $L$. While $γ_n(L)\subseteqδ_n(L)$ for all $n\geq 1$, the two series can differ. In this paper it is proved that if $L$ is a metabelian Lie ring, then $2δ_n(L)\subseteqγ_n(L)$, and $[δ_n(L),\,L]=γ_{n+1}(L)$, for all $n\geq 1$.
For normal subgoups $R$ and $S$ of a free group $F$, an identification of the subgroup $F\cap (1+\mathfrak r\mathfrak f\mathfrak s)$ is derived, and it is shown that the the quotient $\frac{F\cap (1+\mathfrak r\mathfrak f\mathfrak s)}{[R'\cap S',\, R\cap S][R'\cap S,\,R'\cap S][R\cap S',\, R\cap S']}$ is, in general, non-trivial.
Every two-sided ideal $\mathfrak a$ in the integral group ring $\mathbb Z[G] $ of a group $G$ determines a normal subgroup $G \cap (1 + \mathfrak a)$ of $G$. In this paper certain problems related to the identification of such subgroups, and their relationship with derived functors in the sense of Dold-Puppe, are discussed.
An algorithm for the explicit computation of a complete set of primitive central idempotents, Wedderburn decomposition and the automorphism group of the semisimple group algebra of a finite metabelian group is developed. The algorithm is illustrated with its application to the semisimple group algebra of an arbitrary metacyclic group, and certain indecomposable groups whose central quotient is the Klein four-group.
We compare, for L a Lie ring over the integers, its lower central series (γ_n(L))_{n>0} and its dimension series defined by δ_n(L):=L\cap \varpi^n(L) in the universal enveloping algebra of L. We show that γ_n(L)=δ_n(L) for all n<4, but give an example showing that they may differ if n=4. We introduce simplicial methods to describe these results, and to serve as a possible tool for further study of the dimension series.
In this paper homotopical methods for the description of subgroups determined by ideals in group rings are introduced. It is shown that in certain cases the subgroups determined by symmetric product of ideals in group rings can be described with the help of homotopy groups of spheres.
We consider limits over categories of extensions and show how certain well-known functors on the category of groups turn out as such limits. We also discuss higher (or derived) limits over categories of extensions.