Following Schubert varieties under Feigin's degeneration of the flag variety
arXiv:1802.04320
Abstract
We describe the effect of Feigin's flat degeneration of the type flag variety on its Schubert varieties. In particular, we study when they stay irreducible and in several cases we are able to encode reducibility of the degenerations in terms of symmetric group combinatorics. As a side result, we obtain an identification of some Schubert varieties with Richardson varieties in higher rank partial flag varieties.
Comments are welcome! 25 pages + Appendix (5 pages), 2 figures, section 3 improved