Ed Richmond

Let G be a simple Lie group or Kac-Moody group and P a parabolic subgroup. One of the goals Schubert calculus is to understand the product structure of the cohomology ring H^*(G/P) with respect to its basis of Schubert classes. If G/P is the...

A theorem of Ryan and Wolper states that a type A Schubert variety is smooth if and only if it is an iterated fibre bundle of Grassmannians. We extend this theorem to arbitrary finite type, showing that a Schubert variety in a generalized flag...