Nullitope

The nullitope, or nulloid, is the simplest polytope possible. It has no elements, and it may be considered an element of every other polytope. By convention, it is said to have a rank of &minus;1. While a point has a location but no other properties, a nullitope does not even have location, although it is sometimes said to be located at infinity.

Other names for it have been null polytope, nought, wessian, essence, namon, nullon or simply empty element.

It describes the bottom node of the Hasse diagram of any polytope.