Circle of a sphere the Equator the only great circle. By contrast, all meridians of longitude, paired with their opposite meridian in the other hemisphere, form great circles. The diameter of the sphere which passes through the center of the circle is called its axis and the endpoints of this diameter are called its poles. A circle of a sphere can also be defined as the set of points at a given angular distance from a given pole. When the intersection of a sphere and a plane is not empty or a single point, it is a circle. This can be seen as follows:
Simplicial sphere "i"-faces of any simplicial "d"-sphere with "f" = "n" vertices. This conjecture was proved for polytopal spheres by Peter McMullen in 1970 and by Richard Stanley for general simplicial spheres in 1975. The g"-conjecture, formulated by McMullen in 1970, asks for a complete characterization of "f"-vectors of simplicial "d"-spheres. In other words, what are the possible sequences of numbers of faces of each dimension for a simplicial "d"-sphere? In the case of polytopal spheres, the answer is given by the g"-theorem, proved in 1979 by Billera and Lee (existence) and Stanley (necessity). It has been conjectured that the same conditions