THE SEN CONJECTURE FOR DISTINCT FUNDAMENTAL MONOPOLES

I review some recent progress in our understanding of the interactions of BPS monopoles for higher lank groups. S-duality predicts the exist ence of a middle-dimensional square integrable harmonic form on the mo duli space of distinct fundamental BPS monopoles of an arbitrary Lie g roup. These harmonic forms are exhibited and the their uniqueness is d iscussed. The properties of distinct fundamantal monopoles are contras ted with those of identical SU(2) monopoles.