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Interval Deformations of Coxeter Arrangements
Abstract
We study integer-interval deformations of Coxeter arrangements of types A, B, and D, assigning an integer interval to each root direction through an integer-valued root function. We introduce a local compatibility condition on this root function. For compatible root functions, subject to additional local bounds in types B and D, we derive characteristic-polynomial formulas as binomial sums over cyclic orders in type A and signed permutations in types B and D. The proofs use the finite-field method and reduce hyperplane avoidance to consecutive-gap inequalities. These formulas recover, in particular, the classical Catalan and Shi characteristic polynomials.
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BibTeX
@misc{chen2026interval,
title = {{Interval Deformations of Coxeter Arrangements}},
author = {Yanru Chen and Ang Li and Suijie Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.29203},
eprint = {2608.29203},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.29203},
}
RIS
TY - UNPB
TI - Interval Deformations of Coxeter Arrangements
AU - Yanru Chen
AU - Ang Li
AU - Suijie Wang
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2608.29203
UR - https://arxiv.org/abs/2608.29203
AB - We study integer-interval deformations of Coxeter arrangements of types A, B, and D, assigning an integer interval to each root direction through an integer-valued root function. We introduce a local compatibility condition on this root function. For compatible root functions, subject to additional local bounds in types B and D, we derive characteristic-polynomial formulas as binomial sums over cyclic orders in type A and signed permutations in types B and D. The proofs use the finite-field method and reduce hyperplane avoidance to consecutive-gap inequalities. These formulas recover, in particular, the classical Catalan and Shi characteristic polynomials.
ER -