2025/08/18 by Shao-Hua Liu, Liu, Shao-Hua
Mathematics · #Advanced Mathematical Identities #Advanced Combinatorial Mathematics #Mathematical Inequalities and Applications
paper · pdf · doi:10.48550/arxiv.2508.12717
Recently, we proved the equidistribution of the pairs of permutation statistics (r\textsfdes,r\textsfmaj) and (r\textsfexc,r\textsfden). Any pair of permutation statistics that is equidistributed with these pairs is said to be r-Euler--Mahonian. Several classes of r-Euler--Mahonian statistics were established by Huang--Lin--Yan and Huang--Yan. Inspired by their bijections, we provide a new bijective proof of the classical result that (\textsfexc,\textsfden) is Euler--Mahonian. Using this bijection, we further show that (\textsfexcr,\textsfden) is r-Euler--Mahonian, where \textsfexcr denotes the number of r-level excedances (i.e., excedances at least r). Furthermore, by extending our bijection, we establish a more general result that encompasses all the aforementioned results.