English

Shuffling functors and spherical twists on $D^\mathrm b(\mathcal O_0)$

Representation Theory 2021-03-30 v4

Abstract

For a semisimple complex Lie algebra g\mathfrak g, the BGG category O\mathcal{O} is of particular interest in representation theory. It is known that Irving's shuffling functors Shw\mathrm{Sh}_{w}, indexed by elements wWw\in W of the Weyl group, induce an action of the braid group BWB_W associated to WW on the derived categories Db(Oλ)D^\mathrm{b}(\mathcal{O}_\lambda) of blocks of O\mathcal{O}. We show that for maximal parabolic subalgebras p\mathfrak{p} of sln\mathfrak{sl}_n corresponding to the parabolic subgroup Wp=Sn1×S1W_\mathfrak{p}=S_{n-1}\times S_1 of SnS_n, the derived shuffling functors LShsi\mathbf{L}\mathrm{Sh}{s_i} are instances of Seidel and Thomas' spherical twist functors. Namely, we show that certain parabolic indecomposable projectives Pp(w)P^\mathfrak{p}(w) are spherical objects, and the associated twist functors are naturally isomorphic to LShw[1]\mathbf{L}\mathrm{Sh}{w}[1] as auto-equivalences of Db(Op)D^\mathrm{b}(\mathcal{O}^\mathfrak{p}). We give an overview of the main properties of the BGG category O\mathcal{O}, the construction of shuffling and spherical twist functors, and give some examples how to determine images of both. To this end, we employ the equivalence of blocks of O\mathcal{O} and the module categories of certain path algebras.

Keywords

Cite

@article{arxiv.2002.10700,
  title  = {Shuffling functors and spherical twists on $D^\mathrm b(\mathcal O_0)$},
  author = {Fabian Lenzen},
  journal= {arXiv preprint arXiv:2002.10700},
  year   = {2021}
}

Comments

31 pages

R2 v1 2026-06-23T13:52:41.497Z