Two graphs with adjacency matrices \mathbf{A} and \mathbf{B} are isomorphic if there exists a permutation matrix \mathbf{P} for which the identity \mathbf{P}^{\mathrm{T}} \mathbf{A} \mathbf{P} = \mathbf{B} holds. Multiplying through by \mathbf{P} and relaxing the permutation matrix to a doubly stochastic matrix leads to the notion of fractional isomorphism. We show ... more >>>