Nilpotent orbits of linear and cyclic quivers and Kazhdan-Lusztig   polynomials of type A
  The intersection cohomologies of closures of nilpotent orbits of linear (respectively, cyclic) quivers are known to be described by Kazhdan-Lusztig polynomials for the symmetric group (respectively, the affine symmetric group). We explain how to simplify this description using a combinatorial cancellation procedure, and derive some consequences for representation theory. 
Anthony Henderson