Following recent work of Brenti and Carnevale, we investigate a sign-twisted Poincaré series for finite Weyl groups that tracks “odd inversions”; i.e. the number of odd-height positive roots transformed into negative roots by each member of . We prove that the series is divisible by the corresponding series for any parabolic subgroup , and provide sufficient conditions for when the quotient of the two series equals the restriction of the first series to coset representatives for . We also show that the series has an explicit factorization involving the degrees of the free generators of the polynomial invariants of a canonically associated reflection group.
Revised: 2019-01-17
Accepted: 2019-01-21
Published online: 2019-08-01
DOI: https://doi.org/10.5802/alco.62
Classification: 05E15, 05A19, 20F55
Keywords: Weyl group, root system, Poincaré series, inversion
@article{ALCO_2019__2_4_621_0, author = {Stembridge, John R.}, title = {Sign-twisted Poincar\'e series and odd inversions in Weyl groups}, journal = {Algebraic Combinatorics}, pages = {621--644}, publisher = {MathOA foundation}, volume = {2}, number = {4}, year = {2019}, doi = {10.5802/alco.62}, mrnumber = {3997515}, zbl = {1417.05246}, language = {en}, url = {https://alco.centre-mersenne.org/item/ALCO_2019__2_4_621_0/} }
Stembridge, John R. Sign-twisted Poincaré series and odd inversions in Weyl groups. Algebraic Combinatorics, Volume 2 (2019) no. 4, pp. 621-644. doi : 10.5802/alco.62. https://alco.centre-mersenne.org/item/ALCO_2019__2_4_621_0/
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