English

Stable map quotients (and orbifold log resolutions) of Richardson varieties

Algebraic Geometry 2025-05-16 v1

Abstract

Let Xλμ:=XλXμG/PX_\lambda^\mu := X_\lambda \cap X^\mu \subseteq G/P be a Richardson variety in a generalized partial flag manifold. We use equivariant stable map spaces to define a canonical resolution Xλμ~\widetilde{X_\lambda^\mu} of singularities, albeit obtaining an orbifold not a manifold. The ``nodal curves'' boundary is an (orbifold) simple normal crossings divisor, and is conjecturally anticanonical. Its dual simplicial complex is the order complex of the open Bruhat interval (λ,μ)W/WP(\lambda,\mu) \subseteq W/W_P, shown in [Bj\"orner-Wachs '82] to be a sphere or ball. In the case of G/PG/P a Grassmannian, the resolution Xλμ~\widetilde{X_\lambda^\mu} is a GKM space, whose TT-fixed points are indexed by rim-hook tableaux.

Keywords

Cite

@article{arxiv.2505.09905,
  title  = {Stable map quotients (and orbifold log resolutions) of Richardson varieties},
  author = {Allen Knutson},
  journal= {arXiv preprint arXiv:2505.09905},
  year   = {2025}
}

Comments

25 pages