Bicolored Eulerian quasisymmetric functions, affine lengths, and Theta operators
Abstract
We introduce a q-analogue of the bicolored Eulerian quasisymmetric functions by incorporating an additional grading arising from affine length, obtained by interpreting bicolored permutations as affine permutations. We also provide an intrinsic description of this refinement in terms of bicolored permutations by introducing notions of alignments and crossings, together with an explicit bijection identifying these statistics with the alignments and crossings in the existing literature. Finally, we prove that our refinement is symmetric by expressing it in terms of the Theta operators appearing in the Theta coinvariant Conjecture and the modified Macdonald symmetric functions. Assuming the Theta coinvariant conjecture implies the Schur-positivity of our refinement.
Related
- A family of algebras that connects positroids, the Theta conjecture, the Delta conjecture, and Eulerian quasisymmetric functions
- The universal property of the decomposition space of quasisymmetric functions
- Chromatic word-quasisymmetric functions of matroids
- Eulerian insertion operators and an Eulerian form of the Pieri rule
- Optimal lengths of commutators of idempotents and similarity of nilpotent operators to their negatives
BibTeX
@misc{liao2026bicolored,
title = {{Bicolored Eulerian quasisymmetric functions, affine lengths, and Theta operators}},
author = {Hsin-Chieh Liao and Hai Zhu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19363},
eprint = {2610.19363},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19363},
}
RIS
TY - UNPB
TI - Bicolored Eulerian quasisymmetric functions, affine lengths, and Theta operators
AU - Hsin-Chieh Liao
AU - Hai Zhu
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.19363
UR - https://arxiv.org/abs/2610.19363
AB - We introduce a q-analogue of the bicolored Eulerian quasisymmetric functions by incorporating an additional grading arising from affine length, obtained by interpreting bicolored permutations as affine permutations. We also provide an intrinsic description of this refinement in terms of bicolored permutations by introducing notions of alignments and crossings, together with an explicit bijection identifying these statistics with the alignments and crossings in the existing literature. Finally, we prove that our refinement is symmetric by expressing it in terms of the Theta operators appearing in the Theta coinvariant Conjecture and the modified Macdonald symmetric functions. Assuming the Theta coinvariant conjecture implies the Schur-positivity of our refinement.
ER -