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JOURNAL OF
ALGEBRAIC
COMBINATORICS

  Editors-in-chief: C. A. Athanasiadis, T. Lam, A. Munemasa, H. Van Maldeghem
ISSN 0925-9899 (print) • ISSN 1572-9192 (electronic)
 

Aspects of the conjugacy class structure of simple algebraic groups

Martin Cook

DOI: 10.1007/s10801-009-0187-y

Abstract

Let G be an adjoint simple algebraic group over an algebraically closed field of characteristic p; let Φ  be the root system of G, and take t\in \Bbb N. Lawther has proven that the dimension of the set G [ t]={ g\in  G: g t =1} depends only on Φ  and  t. In particular the value is independent of the characteristic p; this was observed for t small and prime by Liebeck. Since G [ t] is clearly a disjoint union of conjugacy classes the question arises as to whether a similar result holds if we replace G [ t] by one of those classes. This paper provides a partial answer to that question. A special case of what we have proven is the following. Take p, q to be distinct primes and G p and G q to be adjoint simple algebraic groups with the same root system and over algebraically closed fields of characteristic p and q respectively. If s\in  G p has order q then there exists an element u\in  G q such that o( u)= o( s) and = s^G_p \dim u^{G_{q}}=\dim s^{G_{p}} .

Pages: 319–353

Keywords: keywords algebraic groups; conjugacy classes; characteristic independent

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