Unipotent Variety in the Group Compactification
نویسندگان
چکیده
Abstract. The unipotent variety of a reductive algebraic group G plays an important role in the representation theory. In this paper, we will consider the closure Ū of the unipotent variety in the De Concini-Procesi compactification Ḡ of a quasisimple, adjoint group G. We will prove that Ū − U is a union of some G-stable pieces introduced by Lusztig in [L4]. This was first conjectured by Lusztig. We will also give an explicit description of Ū . It turns out that the similar results hold for the closure of the Steinberg fiber in Ḡ.
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