English

Torus fixed point sets of Hessenberg Schubert varieties in regular semisimple Hessenberg varieties

Algebraic Geometry 2022-02-09 v2 Combinatorics

Abstract

It is well-known that the TT-fixed points of a Schubert variety in the flag variety GLn(C)/BGL_n(\mathbb{C})/B can be characterized purely combinatorially in terms of Bruhat order on the symmetric group Sn\mathfrak{S}_n. In a recent preprint, Cho, Hong, and Lee give a combinatorial description of the TT-fixed points of Hessenberg analogues of Schubert varieties (which we call Hessenberg Schubert varieties) in a regular semisimple Hessenberg variety. This note gives an interpretation of their result in terms of Bruhat order by making use of a partition of the symmetric group defined using so-called subsets of Weyl type. The Appendix, written by Michael Zeng, proves a lemma concerning subsets of Weyl type which is required in our arguments.

Keywords

Cite

@article{arxiv.2112.13250,
  title  = {Torus fixed point sets of Hessenberg Schubert varieties in regular semisimple Hessenberg varieties},
  author = {Megumi Harada and Martha Precup},
  journal= {arXiv preprint arXiv:2112.13250},
  year   = {2022}
}

Comments

13 pages. Major revision, due to an error discovered in the proof of the main theorem of the previous version. The current version states and proves a revised result, which concerns the T-fixed points of the Hessenberg Schubert variety instead of the variety itself