References

3, ds2) with ds2 = dx2 + dy2 + [dz + 1 2 (ydx − xdy)]2, invariant by rotations about the z-axis. Here one finds a complete descrip-tion of all rotational surfaces with constant Gauss curvatureK in the Heisen-berg space H3. Despite many and substantial similarities with the Euclidean case, this family of surfaces displays some phenomena which do not have their counterpart in R3. For K = 0 there are three cases, for K> 0 also three cases, but for K < 0 five cases. The profile curves of all these case