Ricerc@Sapienza

Quiver Grassmannians are projective varieties parametrizing subrepresentations
of given dimension in a quiver representation. We define a class of quiver Grassmannians
generalizing those which realize degenerate flag varieties. We show that each irreducible
component of the quiver Grassmannians in question is isomorphic to a Schubert variety.We
give an explicit description of the set of irreducible components, identify all the Schubert
varieties arising, and compute the Poincar´e polynomials of these quiver Grassmannians.