On Convex Polyhedra in Lobačevskiĭ Spaces

This paper is concerned with the investigation of properties of convex polyhedra in Lobacevskiĭ spaces; it gives a complete description of convex bounded polyhedra with dihedral angles not exceeding 90, in a three-dimensional Lobacevskiĭ space. This in turn permits a description of the discrete groups generated by reflections acting in the three-dimensional Lobacevskiĭ space with a compact fundamental region.6 figures; bibliography: 6 items.