Poisson reduction of the lattice Kac–Moody algebra

The poisson reduction of the $SL(N)$ lattice Kac–Moody algebra under the action of the maximal nilpotent subgroup of $SL(N)$ is considered. Poisson brackets on the reduced phase space are constructed. For $N=2$ in the continuous limit they comprise with the Gelfand–Fuchs cocycle.