11-cell
From Biocrawler, the free encyclopedia.
In mathematics, the 11-cell is a four-dimensional self-dual abstract regular polytope. Its facets are hemi-icosahedral, and as its name implies, are 11 in number. It also has 11 vertices, 55 edges and 55 ridges. Its symmetry group is the projective special linear group L2(11), so it has 660 symmetries. It has Schläfli symbol {3,5,3}.
It was discovered by Branko Grünbaum in 1977, who constructed it by pasting hemi-icosahedra together, three per edge until the shape closed up. It was independently discovered by H. S. M. Coxeter in 1984, who studied its structure and symmetry in greater depth.
