English

$q$-enumeration of type B and D Eulerian polynomials based on parity of descents

Combinatorics 2026-04-10 v3

Abstract

Carlitz and Scoville in 1973 considered a four variable polynomial that enumerates permutations in Sn\mathfrak{S}_n with respect to the parity of its descents and ascents. In recent work, Pan and Zeng proved a qq-analogue of Carlitz-Scoville's generating function by enumerating permutations with the above four statistice along with the inversion number. Further, they also proved a type B analogue by enumerating signed permutations with respect to the parity of descents and ascents. In this work we prove a qq-analogue of the type B result of Pan and Zeng by enumerating permutations in Bn\mathfrak{B}_n with the above four statistics and the type B inversion number. We also obtain a qq-analogue of the generating function for the type B bivariate alternating descent polynomials. We consider a similar five-variable polynomial in the type D Coxeter groups as well and give their egf. Alternating descents for the type D groups were previously also defined by Remmel, but our definition is slightly different. As a by-product of our proofs, we get bivariate qq-analogues of Hyatt's recurrences for the type B and type D Eulerian polynomials. Further corollaries of our results are some symmetry relations for these polynomials and qq-analogues of generating functions for snakes of types B and D.

Keywords

Cite

@article{arxiv.2211.15277,
  title  = {$q$-enumeration of type B and D Eulerian polynomials based on parity of descents},
  author = {Hiranya Kishore Dey and Umesh Shankar and Sivaramakrishnan Sivasubramanian},
  journal= {arXiv preprint arXiv:2211.15277},
  year   = {2026}
}

Comments

27 pages. Comments are welcome