English

Torus quotients of Richardson varieties in the Grassmannian

Representation Theory 2019-01-08 v1 Algebraic Geometry

Abstract

We study the GIT quotient of the minimal Schubert variety in the Grassmannian admitting semistable points for the action of maximal torus TT, with respect to the TT-linearized line bundle L(nωr){\cal L}(n \omega_r) and show that this is smooth when gcd(r,n)=1gcd(r,n)=1. When n=7n=7 and r=3r=3 we study the GIT quotients of all Richardson varieties in the minimal Schubert variety. This builds on previous work by Kumar \cite{kumar2008descent}, Kannan and Sardar \cite{kannan2009torusA}, Kannan and Pattanayak \cite{kannan2009torusB}, and recent work of Kannan et al \cite{kannan2018torus}. It is known that the GIT quotient of G2,nG_{2,n} is projectively normal. We give a different combinatorial proof.

Keywords

Cite

@article{arxiv.1901.01043,
  title  = {Torus quotients of Richardson varieties in the Grassmannian},
  author = {Sarjick Bakshi and S. Senthamarai Kannan and K. Venkata Subrahmanyam},
  journal= {arXiv preprint arXiv:1901.01043},
  year   = {2019}
}