4 21 polytope

In 8-dimensional geometry, the 4₂₁ is a semiregular uniform 8-polytope, constructed within the symmetry of the E₈ group. It was discovered by Thorold Gosset, published in his 1900 paper. He called it an 8-ic semi-regular figure.

Its Coxeter symbol is 4₂₁, describing its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of the 4-node sequences, .

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