  Matrix string theory (or more generally U-Duality) requires Super Yang-Mills
theory to reflect a stringy degeneracy of BPS short multiplets. These are found
as supersymmetric states in the Yang-Mills carrying (fractionated) momentum, or
in some cases, instanton number. Their energies also agree with those expected
from M(atrix) theory. A nice parallel also emerges in the relevant cases,
between momentum and instanton number, (both integral as well as fractional)
providing evidence for a recent conjecture relating the two.
