  The classification of equilibria for the spatially homogeneous Boltzmann
equation for Fermi-Dirac particles is proved for any $n$-dimensional velocity
space with $n\ge 2$. The same classification has been proven in \cite{Lu2001}
for $n=3$. Now the proof for $n\ge 2$ is based on a recent result on a
characterization of Euclidean balls for all dimensions $\ge 2$.
