  For a system of N bosons in a 2d harmonic trap with frequency omega,
interacting via repulsive forces V<<omega, we develop supersymmetric method to
find the lowest energy states of rotating Bose condensate as function of two
quantum numbers, the total angular momentum and the angular momentum of
internal excitations (generalized yrast states). The energies of these
condensed vortex states are expressed through the single two-body matrix
element of interaction V. A broad universality class of the repulsive
interactions for which these results hold is described by a simple integral
condition on V. It includes Gaussian, delta-function and log-Coulomb forces.
