English

Cyclic sieving phenomena on parabolic classes of faces of the cluster complex

Combinatorics 2026-03-31 v1

Abstract

The cyclic sieving phenomenon was introduced by Reiner, Stanton and White in 2004 as a generalization of Stembridge's q=1q=-1 phenomenon. In a paper from 2008, Eu and Fu studied many occurrences of this phenomenon on the faces of the generalized cluster complex with the action of the Fomin-Reading rotation in the classical types AnA_n, BnB_n, DnD_n and I2(k)I_2(k). There was yet no known uniform qq-analogue of the kk-face numbers of these complexes. In a more recent paper from 2023, Douvropoulos and Josuat-Verg\`es provided a refinement of the enumeration of the faces of the generalized cluster complex using a uniform formula. For a parabolic subgroup WXWW_X \subset W of the associated Coxeter group WW, their formula factorises nicely under the assumption that NW(WX)/WXN_W(W_X)/W_X acts as a reflection group on XX, which is very often the case. Using this condition, we provide a uniform refinement of these cyclic sieving phenomena using a qq-analogue of their main formula with a type by type proof based on the classification of finite irreducible Coxeter groups.

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Cite

@article{arxiv.2603.28242,
  title  = {Cyclic sieving phenomena on parabolic classes of faces of the cluster complex},
  author = {Lucas Pouillart},
  journal= {arXiv preprint arXiv:2603.28242},
  year   = {2026}
}

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34 pages