The action of the group G0 of fixed points of a semisimple automorphism θ of a reductive algebraic group G on an eigenspace V of this automorphism in the Lie algebra g of the group G is considered.… Expand

CONTENTSIntroductionChapter I. Acute-angled polytopes in Lobachevskii spaces § 1. The Gram matrix of a convex polytope § 2. The existence theorem for an acute-angled polytope with given Gram matrix §… Expand

Discrete groups of motions of spaces of constant curvature, as well as other groups that can be regarded as such (although they may be defined differently), arise naturally in different areas of… Expand