Abstract: Let G be a linear algebraic group defined over an algebraically closed field. We consider various properties of the unipotent elements of G, its conjugacy classes, the nilpotent G-orbits in the Lie algebra of G, and overgroups of unipotent elements in G, basing our first observations on the group SL_n(C), and then turning to the case of semisimple algebraic groups defined over arbitrary algebraically closed fields. In particular, we discuss the classical results of Springer and Steinberg, which hold in most characteristics.

We then turn to the recent work of Liebeck and Seitz, Lawther and Testerman, and Lawther, on centralizers and abelian overgroups of unipotent elements in small characteristics.

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ab  15:45 Uhr,
Arnimallee 3,  Raum 006