Simple look at supersymmetric N=2 gauge theory with arbitrary gauge   group
  A new discrete symmetry is shown to govern and simplify low-energy properties of the supersymmetric N=2 gauge theory with an arbitrary gauge group. Each element of the related symmetry group S_r, r being the rank of the gauge group, represents a permutation of r electric charges available in the theory accompanied by a concurrent permutation of r monopoles, provided the sets of charges and monopoles are chosen properly. The superpotential is symmetric under S_r. This symmetry strongly manifests itself for the degenerate case; when the masses of r electric charges are chosen to be equal, then the masses of r monopoles are necessarily degenerate as well, and vice versa. This condition uniquely defines the vital for the theory VEV of the scalar field, which makes all monopoles massless. 
Michael Kuchiev
hep-th