scholarly journals Groups whose irreducible representations have finite degree II

1982 ◽  
Vol 25 (3) ◽  
pp. 237-243 ◽  
Author(s):  
B. A. F. Wehrfritz
Keyword(s):  
Characteristic Zero ◽  
Finite Dimension ◽  
Irreducible Representations ◽  
Finitely Generated ◽  
Finite Degree ◽  
Commutative Field ◽  
Soluble Groups

If F is a (commutative) field let denote the class of all groups G such that every irreducible FG-module has finite dimension over F. The introduction to [7] contains motivation for considering these classes and surveys some of the results to date concerning them. In [7] for every field F we determined the finitely generated soluble groups in . Here, for fields F of characteristic zero, we determine, at least in principle, the soluble groups in . Our main result is the following.

Groups whose irreducible representations have finite degree: III

1982 ◽  
Vol 91 (3) ◽  
pp. 397-406 ◽  
Author(s):  
B. A. F. Wehrfritz
Keyword(s):  
Characteristic Zero ◽  
Positive Characteristic ◽  
Finite Dimension ◽  
Irreducible Representations ◽  
Finitely Generated ◽  
Finite Degree ◽  
Commutative Field

If F is a (commutative) field let XF denote the class of all groups G such that every irreducible FG module has finite dimension over F. In the first paper (9) of this series we classified finitely generated soluble XF-groups for each field F and in the second (10) we characterized soluble XF-groups for each field F of characteristic zero. Here we consider soluble XF-groups over fields F of positive characteristic.

Groups whose irreducible representations have finite degree

1981 ◽  
Vol 90 (3) ◽  
pp. 411-421 ◽  
Author(s):  
B. A. F. Wehrfritz
Keyword(s):  
Nilpotent Group ◽  
Positive Solution ◽  
Finite Dimension ◽  
Systematic Investigation ◽  
Polycyclic Group ◽  
Irreducible Representations ◽  
Finitely Generated ◽  
Finite Degree ◽  
Commutative Field ◽  
Locally Finite

Throughout this paper F denotes a (commutative) field. Let XF denote the class of all groups G such that every irreducible FC-module has finite dimension over F. In (1) P. Hall showed that if F is not locally finite and if G is polycyclic, then G∈XF if and only if G is abelian-by-finite. Also in (1), if F is locally finite he proved that every finitely generated nilpotent group is in XF and he conjectured that XF should contain every polycyclic group. This turned out to be very difficult, but a positive solution was eventually found by Roseblade, see (8). Meanwhile Levič in (4) had started a systematic investigation of the classes XF. Although his paper contains a number of errors, obscurities and omissions, it remains an interesting work, and it, or more accurately its recent translation, stimulated this present paper.

Faithful Representations of Finitely Generated Metabelian Groups

1975 ◽  
Vol 27 (6) ◽  
pp. 1355-1360 ◽  
Author(s):  
B. A. F. Wehrfritz
Keyword(s):  
Finite Index ◽  
Characteristic Zero ◽  
Metabelian Group ◽  
Finite Extension ◽  
Faithful Representation ◽  
Finitely Generated ◽  
Finite Degree ◽  
Metabelian Groups ◽  
Finite Exponent ◽  
Torsion Free

In [3] Remeslennikov proves that a finitely generated metabelian group G has a faithful representation of finite degree over some field F of characteristic zero (respectively, p > 0) if its derived group G’ is torsion-free (respectively, of exponent p). By the Lie-Kolchin-Mal'cev theorem any metabelian subgroup of GL(n, F) has a subgroup of finite index whose derived group is torsion-free if char F = 0 and is a p-group of finite exponent if char F = p > 0. Moreover every finite extension of a group with a faithful representation (of finite degree) has a faithful representation over the same field. Thus Remeslennikov's results have a gap which we propose here to fill.

scholarly journals The Representations of Lie Algebras of Prime Characteristic

1954 ◽  
Vol 2 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Hans Zassenhaus
Keyword(s):  
Lie Algebra ◽  
Lie Algebras ◽  
Characteristic Zero ◽  
Finite Dimension ◽  
Quotient Ring ◽  
Irreducible Representations ◽  
Indecomposable Representation ◽  
Prime Characteristic ◽  
Representations Of Lie Algebras ◽  
Algebra Over A Field

There are some simple facts which distinguish Lie-algebras over fields of prime characteristic from Lie-algebras over fields of characteristic zero. These are(1) The degrees of the absolutely irreducible representations of a Lie-algebra of prime characteristic are bounded whereas, according to a theorem of H. Weyl, the degrees of the absolutely irreducible representations of a semi-simple Lie-algebra over a field of characteristic zero can be arbitrarily high.(2) For each Lie-algebra of prime characteristic there are indecomposable representations which are not irreducible, whereas every indecomposable representation of a semi-simple Liealgebra over a field of characteristic zero is irreducible (cf. [4]).(3) The quotient ring of the embedding algebra of a Lie-algebra over a field of prime characteristic is a division algebra of finite dimension over its center, whereas this is not the case for characteristic zero. (cf. [4]).(4) There are faithful fully reducible representations of every Lie-algebra of prime characteristic, whereas for characteristic zero only ring sums of semi-simple Lie-algebras and abelian Lie-algebras admit faithful fully reducible representations (cf. [6], [2], [4]).

scholarly journals On the primitive irreducible representations of finitely generated nilpotent groups

2021 ◽  
pp. 24-27
Author(s):  
A.V. Tushev
Keyword(s):  
Irreducible Representation ◽  
Nilpotent Group ◽  
Commutative Algebra ◽  
Characteristic Zero ◽  
Nilpotent Groups ◽  
Irreducible Representations ◽  
Finitely Generated ◽  
Primitive Representation

We develop some tecniques whish allow us to apply the methods of commutative algebra for studing the representations of nilpotent groups. Using these methods, in particular, we show that any irreducible representation of a finitely generated nilpotent group G over a finitely generated field of characteristic zero is induced from a primitive representation of some subgroup of G.

Existence of Weight Space Decompositions for Irreducible Representations of Simple Lie Algebras

1971 ◽  
Vol 14 (1) ◽  
pp. 113-115 ◽  
Author(s):  
F. W. Lemire
Keyword(s):  
Irreducible Representation ◽  
Lie Algebra ◽  
Lie Algebras ◽  
Characteristic Zero ◽  
Finite Dimension ◽  
Irreducible Representations ◽  
Weight Space ◽  
Closed Field ◽  
Space Decomposition ◽  
Finite Dimensional

Let L denote a finite-dimensional simple Lie algebra over an algebraically closed field K of characteristic zero. It is well known that every finite-dimension 1, irreducible representation of L admits a weight space decomposition; moreover every irreducible representation of L having at least one weight space admits a weight space decomposition.

scholarly journals On the primitive irreducible representations of finitely generated linear groups of finite rank

2021 ◽  
pp. 2250068
Author(s):  
A. V. Tushev
Keyword(s):  
Linear Group ◽  
Finite Rank ◽  
Characteristic Zero ◽  
Irreducible Representations ◽  
Linear Groups ◽  
Finitely Generated ◽  
Primitive Representation

In the paper, we study finitely generated linear groups of finite rank which have faithful irreducible primitive representations over a field of characteristic zero. We prove that if an infinite finitely generated linear group [Formula: see text] of finite rank has a faithful irreducible primitive representation over a field of characteristic zero then the [Formula: see text]-center [Formula: see text] of [Formula: see text] is infinite.

scholarly journals A decomposition formula for representations

1987 ◽  
Vol 107 ◽  
pp. 63-68 ◽  
Author(s):  
George Kempf
Keyword(s):  
Irreducible Representation ◽  
General Formula ◽  
Parabolic Subgroup ◽  
Characteristic Zero ◽  
Maximal Torus ◽  
Reductive Group ◽  
Irreducible Representations ◽  
Levi Subgroup ◽  
Know How ◽  
Decomposition Formula

Let H be the Levi subgroup of a parabolic subgroup of a split reductive group G. In characteristic zero, an irreducible representation V of G decomposes when restricted to H into a sum V = ⊕mαWα where the Wα’s are distinct irreducible representations of H. We will give a formula for the multiplicities mα. When H is the maximal torus, this formula is Weyl’s character formula. In theory one may deduce the general formula from Weyl’s result but I do not know how to do this.

ON THE RANK OF ABELIAN VARIETIES OVER AMPLE FIELDS

2010 ◽  
Vol 06 (03) ◽  
pp. 579-586 ◽  
Author(s):  
ARNO FEHM ◽  
SEBASTIAN PETERSEN
Keyword(s):  
Finite Field ◽  
Abelian Variety ◽  
Galois Extension ◽  
Characteristic Zero ◽  
Rational Point ◽  
Abelian Varieties ◽  
Finitely Generated ◽  
Infinite Rank ◽  
Finite Set

A field K is called ample if every smooth K-curve that has a K-rational point has infinitely many of them. We prove two theorems to support the following conjecture, which is inspired by classical infinite rank results: Every non-zero Abelian variety A over an ample field K which is not algebraic over a finite field has infinite rank. First, the ℤ(p)-module A(K) ⊗ ℤ(p) is not finitely generated, where p is the characteristic of K. In particular, the conjecture holds for fields of characteristic zero. Second, if K is an infinite finitely generated field and S is a finite set of local primes of K, then every Abelian variety over K acquires infinite rank over certain subfields of the maximal totally S-adic Galois extension of K. This strengthens a recent infinite rank result of Geyer and Jarden.

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