scholarly journals Local geometry of Jordan classes in semisimple algebraic groups

2020 ◽  
Author(s):  
Filippo Ambrosio ◽  
Giovanna Carnovale ◽  
Francesco Esposito
Keyword(s):  
Algebraic Groups ◽  
Local Geometry ◽  
Semisimple Algebraic Groups

scholarly journals HIGHER DEFORMATIONS OF LIE ALGEBRA REPRESENTATIONS II

2020 ◽  
pp. 1-24
Author(s):  
MATTHEW WESTAWAY
Keyword(s):  
Tensor Product ◽  
Algebraic Groups ◽  
Preceding Paper ◽  
Irreducible Representations ◽  
Product Theorem ◽  
Enveloping Algebras ◽  
Frobenius Kernel ◽  
Frobenius Kernels ◽  
Lie Algebra Representations ◽  
Semisimple Algebraic Groups

Steinberg’s tensor product theorem shows that for semisimple algebraic groups, the study of irreducible representations of higher Frobenius kernels reduces to the study of irreducible representations of the first Frobenius kernel. In the preceding paper in this series, deforming the distribution algebra of a higher Frobenius kernel yielded a family of deformations called higher reduced enveloping algebras. In this paper, we prove that the Steinberg decomposition can be similarly deformed, allowing us to reduce representation theoretic questions about these algebras to questions about reduced enveloping algebras. We use this to derive structural results about modules over these algebras. Separately, we also show that many of the results in the preceding paper hold without an assumption of reductivity.

scholarly journals Representations of Algebraic Groups

1963 ◽  
Vol 22 ◽  
pp. 33-56 ◽  
Author(s):  
Robert Steinberg
Keyword(s):  
Algebraic Group ◽  
Algebraic Groups ◽  
Vector Spaces ◽  
Irreducible Representations ◽  
Simple Groups ◽  
Finite Simple Groups ◽  
Prime Field ◽  
Infinite Degree ◽  
Semisimple Algebraic Groups

Our purpose here is to study the irreducible representations of semisimple algebraic groups of characteristic p 0, in particular the rational representations, and to determine all of the representations of corresponding finite simple groups. (Each algebraic group is assumed to be defined over a universal field which is algebraically closed and of infinite degree of transcendence over the prime field, and all of its representations are assumed to take place on vector spaces over this field.)

scholarly journals Équivalence motivique des groupes algébriques semisimples

2017 ◽  
Vol 153 (10) ◽  
pp. 2195-2213
Author(s):  
Charles De Clercq
Keyword(s):  
Algebraic Group ◽  
Algebraic Groups ◽  
Linear Groups ◽  
Flag Varieties ◽  
Orthogonal Groups ◽  
Special Linear ◽  
Special Linear Groups ◽  
Field Extensions ◽  
Semisimple Algebraic Groups ◽  
Partial Version

We prove that the standard motives of a semisimple algebraic group$G$with coefficients in a field of order$p$are determined by the upper motives of the group $G$. As a consequence of this result, we obtain a partial version of the motivic rigidity conjecture of special linear groups. The result is then used to construct the higher indexes which characterize the motivic equivalence of semisimple algebraic groups. The criteria of motivic equivalence derived from the expressions of these indexes produce a dictionary between motives, algebraic structures and the birational geometry of twisted flag varieties. This correspondence is then described for special linear groups and orthogonal groups (the criteria associated with other groups being obtained in De Clercq and Garibaldi [Tits$p$-indexes of semisimple algebraic groups, J. Lond. Math. Soc. (2)95(2017) 567–585]). The proofs rely on the Levi-type motivic decompositions of isotropic twisted flag varieties due to Chernousov, Gille and Merkurjev, and on the notion of pondered field extensions.

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