English

Poincare polynomials of generic torus orbit closures in Schubert varieties

Algebraic Topology 2020-02-17 v1 Algebraic Geometry Combinatorics

Abstract

The closure of a generic torus orbit in the flag variety G/BG/B of type AA is known to be a permutohedral variety and its Poincare polynomial agrees with the Eulerian polynomial. In this paper, we study the Poincare polynomial of a generic torus orbit closure in a Schubert variety in G/BG/B. When the generic torus orbit closure in a Schubert variety is smooth, its Poincare polynomial is known to agree with a certain generalization of the Eulerian polynomial. We extend this result to an arbitrary generic torus orbit closure which is not necessarily smooth.

Keywords

Cite

@article{arxiv.2002.05855,
  title  = {Poincare polynomials of generic torus orbit closures in Schubert varieties},
  author = {Eunjeong Lee and Mikiya Masuda and Seonjeong Park and Jongbaek Song},
  journal= {arXiv preprint arXiv:2002.05855},
  year   = {2020}
}

Comments

20 pages, 6 figures, 3 tables