3 21 polytope
UNIFORM 7-POLYTOPE
Hess polytope; Gosset 3 21 polytope; Rectified 3 21 polytope; Birectified 3 21 polytope; Hessian polytope
In 7-dimensional geometry, the 321 polytope is a uniform 7-polytope, constructed within the symmetry of the E7 group. It was discovered by Thorold Gosset, published in his 1900 paper.