scholarly journals Saturation rank for finite group schemes: Finite groups and infinitesimal group schemes

2018 ◽  
Vol 30 (2) ◽  
pp. 479-495
Author(s):  
Yang Pan
Keyword(s):  
Finite Group ◽  
Lie Algebras ◽  
Finite Groups ◽  
Positive Characteristic ◽  
Group Scheme ◽  
Closed Field ◽  
Group Schemes ◽  
Frobenius Kernel ◽  
A Finite Group ◽  
Finite Group Schemes

AbstractWe investigate the saturation rank of a finite group scheme defined over an algebraically closed field{\Bbbk}of positive characteristicp. We begin by exploring the saturation rank for finite groups and infinitesimal group schemes. Special attention is given to reductive Lie algebras and the second Frobenius kernel of the algebraic group{\operatorname{SL}_{n}}.

Finite group schemes of p-rank ≤ 1

2017 ◽  
Vol 166 (2) ◽  
pp. 297-323
Author(s):  
HAO CHANG ◽  
ROLF FARNSTEINER
Keyword(s):  
Finite Group ◽  
Lie Algebras ◽  
Group Scheme ◽  
Closed Field ◽  
Difficult Case ◽  
Modular Representation Theory ◽  
Group Schemes ◽  
Restricted Lie Algebras ◽  
A Finite Group ◽  
Finite Group Schemes

AbstractLet be a finite group scheme over an algebraically closed field k of characteristic char(k) = p ≥ 3. In generalisation of the familiar notion from the modular representation theory of finite groups, we define the p-rank rkp() of and determine the structure of those group schemes of p-rank 1, whose linearly reductive radical is trivial. The most difficult case concerns infinitesimal groups of height 1, which correspond to restricted Lie algebras. Our results show that group schemes of p-rank ≤ 1 are closely related to those being of finite or domestic representation type.

CONTINUOUS TIME QUANTUM WALKS AND QUOTIENT GRAPHS

2011 ◽  
Vol 09 (03) ◽  
pp. 1005-1017
Author(s):  
R. SUFIANI ◽  
S. NAMI ◽  
M. GOLMOHAMMADI ◽  
M. A. JAFARIZADEH
Keyword(s):  
Finite Group ◽  
Continuous Time ◽  
Group Scheme ◽  
Quantum Walks ◽  
Normal Subgroups ◽  
Arbitrary Vertex ◽  
Group Schemes ◽  
Time Quantum ◽  
A Finite Group ◽  
Finite Group Schemes

Continuous-time quantum walks (CTQW) over finite group schemes is investigated, where it is shown that some properties of a CTQW over a group scheme defined on a finite group G induces a CTQW over group scheme defined on G/H, where H is a normal subgroup of G with prime index. This reduction can be helpful in analyzing CTQW on underlying graphs of group schemes. Even though this claim is proved for normal subgroups with prime index (using the Clifford's theorem from representation theory), it is checked in some examples that for other normal subgroups or even non-normal subgroups, the result is also true! It means that CTQW over the graph on G, starting from any arbitrary vertex, is isomorphic to the CTQW over the quotient graph on G/H if we take the sum of the amplitudes corresponding to the vertices belonging to the same cosets.

scholarly journals Local duality for representations of finite group schemes

2019 ◽  
Vol 155 (2) ◽  
pp. 424-453 ◽  
Author(s):  
Dave Benson ◽  
Srikanth B. Iyengar ◽  
Henning Krause ◽  
Julia Pevtsova
Keyword(s):  
Finite Group ◽  
Cohomology Ring ◽  
Group Scheme ◽  
Stable Category ◽  
Group Schemes ◽  
Stable Module Category ◽  
Serre Duality ◽  
Stable Module ◽  
A Finite Group ◽  
Finite Group Schemes

A duality theorem for the stable module category of representations of a finite group scheme is proved. One of its consequences is an analogue of Serre duality, and the existence of Auslander–Reiten triangles for the $\mathfrak{p}$-local and $\mathfrak{p}$-torsion subcategories of the stable category, for each homogeneous prime ideal $\mathfrak{p}$ in the cohomology ring of the group scheme.

scholarly journals Cohomology and projectivity of modules for finite group schemes

2001 ◽  
Vol 131 (3) ◽  
pp. 405-425 ◽  
Author(s):  
CHRISTOPHER P. BENDEL
Keyword(s):  
Finite Group ◽  
Representation Theory ◽  
Hopf Algebra ◽  
Group Scheme ◽  
Steenrod Algebra ◽  
Group Schemes ◽  
Finite Dimensional ◽  
A Finite Group ◽  
Finite Group Schemes ◽  
Cocommutative Hopf Algebra

Let G be a finite group scheme over a field k, that is, an affine group scheme whose coordinate ring k[G] is finite dimensional. The dual algebra k[G]* ≡ Homk(k[G], k) is then a finite dimensional cocommutative Hopf algebra. Indeed, there is an equivalence of categories between finite group schemes and finite dimensional cocommutative Hopf algebras (cf. [19]). Further the representation theory of G is equivalent to that of k[G]*. Many familiar objects can be considered in this context. For example, any finite group G can be considered as a finite group scheme. In this case, the algebra k[G]* is simply the group algebra kG. Over a field of characteristic p > 0, the restricted enveloping algebra u([gfr ]) of a p-restricted Lie algebra [gfr ] is a finite dimensional cocommutative Hopf algebra. Also, the mod-p Steenrod algebra is graded cocommutative so that some finite dimensional Hopf subalgebras are such algebras.Over the past thirty years, there has been extensive study of the modular representation theory (i.e. over a field of positive characteristic p > 0) of such algebras, particularly in regards to understanding cohomology and determining projectivity of modules. This paper is primarily interested in the following two questions:Questions1·1. Let G be a finite group scheme G over a field k of characteristic p > 0, and let M be a rational G-module.(a) Does there exist a family of subgroup schemes of G which detects whether M is projective?(b) Does there exist a family of subgroup schemes of G which detects whether a cohomology class z ∈ ExtnG(M, M) (for M finite dimensional) is nilpotent?

Finite Groups with Four Relative Commutativity Degrees

2015 ◽  
Vol 22 (03) ◽  
pp. 449-458 ◽  
Author(s):  
A. Erfanian ◽  
M. Farrokhi D.G.
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Frobenius Group ◽  
Maximal Subgroups ◽  
Frobenius Kernel ◽  
A Finite Group

It is shown that a finite group G has four relative commutativity degrees if and only if G/Z(G) is a p-group of order p3 and G has no abelian maximal subgroups, or G/Z(G) is a Frobenius group with Frobenius kernel and complement isomorphic to ℤp × ℤp and ℤq, respectively, and the Sylow p-subgroup of G is abelian, where p and q are distinct primes.

On the Character Rings of Finite Groups

1963 ◽  
Vol 15 ◽  
pp. 605-612 ◽  
Author(s):  
B. Banaschewski
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Characteristic Zero ◽  
Irreducible Representations ◽  
Roots Of Unity ◽  
Closed Field ◽  
One Dimensional ◽  
Elementary Group ◽  
A Finite Group ◽  
Character Ring

The characters of the representations of a finite group G over a field K of characteristic zero generate a ring oK(G) of functions on G, the K-character ring of G, which is readily seen to be Zϕ1 + . . . + Zϕn, where Z is the ring of rational integers and ϕ1, . . . , ϕn are the characters of the different irreducible representations of G over K. The theorem that every irreducible representation of G over an algebraically closed field Ω of characteristic zero is equivalent to a representation of G over the subfield of Ω which is generated by the g0th roots of unity (g0 the exponent of G) was proved by Brauer (4) via the theorems that(1) OΩ(G) is additively generated by the induced characters of representations of elementary subgroups of G, and(2) the irreducible representations over 12 of any elementary group are induced by one-dimensional subgroup representations (3).

scholarly journals Support varieties for rational representations

2014 ◽  
Vol 151 (4) ◽  
pp. 765-792 ◽  
Author(s):  
Eric M. Friedlander
Keyword(s):  
Finite Groups ◽  
Linear Algebraic Group ◽  
Closed Field ◽  
Infinite Dimensional ◽  
Group Schemes ◽  
The Family ◽  
Close Relationship ◽  
Frobenius Kernels ◽  
Support Varieties ◽  
Finite Group Schemes

We introduce support varieties for rational representations of a linear algebraic group $G$ of exponential type over an algebraically closed field $k$ of characteristic $p>0$. These varieties are closed subspaces of the space $V(G)$ of all 1-parameter subgroups of $G$. The functor $M\mapsto V(G)_{M}$ satisfies many of the standard properties of support varieties satisfied by finite groups and other finite group schemes. Furthermore, there is a close relationship between $V(G)_{M}$ and the family of support varieties $V_{r}(G)_{M}$ obtained by restricting the $G$ action to Frobenius kernels $G_{(r)}\subset G$. These support varieties seem particularly appropriate for the investigation of infinite-dimensional rational $G$-modules.

scholarly journals An Application of Finite Groups to Hopf algebras

2021 ◽  
Vol 14 (3) ◽  
pp. 816-828
Author(s):  
Tahani Al-Mutairi ◽  
Mohammed Mosa Al-shomrani
Keyword(s):  
Finite Group ◽  
Hopf Algebra ◽  
Finite Groups ◽  
Hopf Algebras ◽  
Closed Field ◽  
Algebraically Closed Field ◽  
A Finite Group

Kaplansky’s famous conjectures about generalizing results from groups to Hopf al-gebras inspired many mathematicians to try to find solusions for them. Recently, Cohen and Westreich in [8] and [10] have generalized the concepts of nilpotency and solvability of groups to Hopf algebras under certain conditions and proved interesting results. In this article, we follow their work and give a detailed example by considering a finite group G and an algebraically closed field K. In more details, we construct the group Hopf algebra H = KG and examine its properties to see what of the properties of the original finite group can be carried out in the case of H.

scholarly journals On the Auslander-Reiten quiver of an infinitesimal group

2000 ◽  
Vol 160 ◽  
pp. 103-121 ◽  
Author(s):  
Rolf Farnsteiner
Keyword(s):  
Finite Groups ◽  
Reductive Group ◽  
Group Scheme ◽  
Closed Field ◽  
Characteristic P ◽  
Algebraically Closed Field ◽  
Dynkin Diagrams ◽  
Frobenius Kernel ◽  
Euclidean Type

AbstractLet be an infinitesimal group scheme, defined over an algebraically closed field of characteristic p. We employ rank varieties of -modules to study the stable Auslander-Reiten quiver of the distribution algebra of . As in case of finite groups, the tree classes of the AR-components are finite or infinite Dynkin diagrams, or Euclidean diagrams. We classify the components of finite and Euclidean type in case is supersolvable or a Frobenius kernel of a smooth, reductive group.

scholarly journals Bockstein homomorphisms for Hochschild cohomology of group algebras and of block algebras of finite groups

2017 ◽  
Vol 29 (3) ◽  
Author(s):  
Constantin-Cosmin Todea
Keyword(s):  
Finite Group ◽  
Group Algebra ◽  
Finite Groups ◽  
Hochschild Cohomology ◽  
Product Formula ◽  
Group Algebras ◽  
Closed Field ◽  
Additive Decomposition ◽  
A Finite Group ◽  
Block Algebra

AbstractWe give an explicit approach for Bockstein homomorphisms of the Hochschild cohomology of a group algebra and of a block algebra of a finite group and we show some properties. To give explicit definitions for these maps we use an additive decomposition and a product formula for the Hochschild cohomology of group algebras given by Siegel and Witherspoon in 1999. For an algebraically closed field

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