Each member of the sequence has the previous member as its vertex figure.

The birectified 5-simplex is the vertex figure for the third, the 122.

The rectified 10-simplex is the vertex figure of the 11-demicube.

It can be constructed from a number of different vertex figures.

Their vertex figures are the simplices of one less dimension.

The vertex figure has 4 square faces passing through the center of the model.

Faces on a vertex figure are considered to progress in one direction.

Each has a vertex figure as the previous form.

The rectified 9-simplex is the vertex figure of the 10-demicube.

For example the alternation a vertex figure with 2a.2b.2c is a.3.