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Toward Permutation Bases in the Equivariant...
Journal article

Toward Permutation Bases in the Equivariant Cohomology Rings of Regular Semisimple Hessenberg Varieties

Abstract

Recent work of Shareshian and Wachs, Brosnan and Chow, and Guay-Paquet connects the well-known Stanley–Stembridge conjecture in combinatorics to the dot action of the symmetric group Sn$$S_{n}$$ on the cohomology rings H∗(Hess(S,h))$$H^*({{\mathcal {H}}ess}({\mathsf {S}},h))$$ of regular semisimple Hessenberg varieties. In particular, in order to prove the Stanley–Stembridge conjecture, it suffices to construct (for any Hessenberg function h) a permutation basis of H∗(Hess(S,h))$$H^*({{\mathcal {H}}ess}({\mathsf {S}},h))$$ whose elements have stabilizers isomorphic to Young subgroups. In this manuscript, we give several results which contribute toward this goal. Specifically, in some special cases, we give a new, purely combinatorial construction of classes in the T-equivariant cohomology ring HT∗(Hess(S,h))$$H^*_T({{\mathcal {H}}ess}({\mathsf {S}},h))$$ which form permutation bases for subrepresentations in HT∗(Hess(S,h))$$H^*_T({{\mathcal {H}}ess}({\mathsf {S}},h))$$. Moreover, from the definition of our classes it follows that the stabilizers are isomorphic to Young subgroups. Our constructions use a presentation of the T-equivariant cohomology rings HT∗(Hess(S,h))$$H^*_T({{\mathcal {H}}ess}({\mathsf {S}},h))$$ due to Goresky, Kottwitz, and MacPherson. The constructions presented in this manuscript generalize past work of Abe–Horiguchi–Masuda, Chow, and Cho–Hong–Lee.

Authors

Harada M; Precup M; Tymoczko J

Journal

La Matematica, Vol. 1, No. 1, pp. 263–316

Publisher

Springer Nature

Publication Date

March 1, 2022

DOI

10.1007/s44007-021-00016-5

ISSN

2730-9657

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