  String configurations have been identified in compactified Matrix theory at
vanishing string coupling. We show how the interactions of these strings are
determined by the Yang-Mills gauge field on the worldsheet. At finite string
coupling, this suggests the underlying dynamics is not well-approximated as a
theory of strings. This may explain why string perturbation theory diverges
badly, while Matrix string perturbation theory presumably has a perturbative
expansion with properties similar to the strong coupling expansion of 2d
Yang-Mills theory.
