On a certain family of U(b)-modules
  We report on results of Kra\'skiewicz and the author, and Watanabe on KP modules materializing Schubert polynomials, and filtrations having KP modules as their subquotients. We discuss applications of KP filtrations and ample KP bundles to positivity, due respectively to Watanabe and Fulton. The article corresponds to the talk given by the author at the conference "IMPANGA 15" in April 2015. 
Piotr Pragacz
math.RT math.AG math.CO