Point groups in three dimensions the finite subgroups of SO(3), are: the cyclic groups "C" (the rotation group of a canonical pyramid), the dihedral groups "D" (the rotation group of a uniform prism, or canonical bipyramid), and the rotation groups "T", "O" and "I" of a regular tetrahedron, octahedron/cube and icosahedron/dodecahedron. In particular, the dihedral groups "D", "D" etc. are the rotation groups of plane regular polygons embedded in three-dimensional space, and such a figure may be considered as a degenerate regular prism. Therefore, it is also called a "dihedron" (Greek: solid with two faces), which explains the name "dihedral group". The rotation group of
Three Faces East (1930 film) Three Faces East (1930 film) Three Faces East is a 1930 American Pre-Code film directed by Roy Del Ruth and starring Constance Bennett and Erich von Stroheim. Produced by Daryl Zanuck and released by Warner Brothers it is based on a 1918 Broadway play about World War I spies, "Three Faces East". It was filmed as a silent in 1926. A later remake starred Boris Karloff and Margaret Lindsay in "British Intelligence". The story takes place during World War I. The action opens on a French battlefield. After meeting with German spy Schiller Blacher (Erich von Stroheim), Z-1 (Constance Bennett)