The Birkhoff polytope of the groups $\mathsf{F}_4$ and $\mathsf{H}_4$

Mathieu Dutour Sikiric

Published 2022-12-16Version 1

We compute the set of facets of the polytope which is the convex hull of the Coxeter groups $\mathsf{F}_4$ or $\mathsf{H}_4$: For the group $\mathsf{F}_4$ we found $2$ orbits of facets which contradicts previous results published in \cite{birkhoff}. For the group $\mathsf{H}_4$ we found $1063$ orbits of facets which provides a counterexample to the conjecture of \cite{birkhoff}.