The vector k-constrained KP hierarchy and Sato's Grassmannian
  We use the representation theory of the infinite matrix group to show that (in the polynomial case) the $n$--vector $k$--constrained KP hierarchy has a natural geometrical interpretation on Sato's infinite Grassmannian. This description generalizes the the $k$--reduced KP or Gelfand--Dickey hierarchies. 
Johan van de Leur