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 Dimensional E.C. Classics Only the first issue was called "Three Dimensional E.C. Classics." It was a general EC sampler, recycling stories from EC's non-horror lines: "Crime SuspenStories", "Frontline Combat", "Mad" and "Weird Science". The second issue's reference title was "Three Dimensional Tales from the Crypt of Terror". It recycled stories from EC's horror lines exclusively: "Tales from the Crypt" and "The Vault of Horror". It also recycled the "Tales from the Crypt" Crypt-Keeper as host. But in all other essentials these books were the same: new packages of old stories with all new art, often demanding script changes, for the 3-D format. The