6 papers
On the distributions of the statistics (des, maj, inv) over several classes of permutations
Guo-Niu Han, Kathy Q. Ji, Huan Xiong
We investigate the joint distribution of the trivariate statistics (des, maj, inv) on classical permutations, Andre permutations of the first and second kinds, and Simsun permutati…
-Derivative Grammar
Guo-Niu Han, Kathy Q. Ji, Huan Xiong
Context-free grammars, originating in computer science, are related to enumerative combinatorics through two distinct lines of development pioneered by Schützenberger and Chen, res…
Modular Nahm sums for symmetrizable matrices of indices and
Julia Q. D. Du, Kathy Q. Ji, Erin Y. Y. Shen +1
In this paper, we present three families of modular Nahm sums for symmetrizable matrices with arbitrary rank of indices and . Speci…
Inverse descent statistic for André and simsun permutations
Guo-Niu Han, Kathy Q. Ji, Huan Xiong
Simsun permutations, André I permutations and André II permutations are three combinatorial models for Euler numbers. It's known that the descent statistic is equidistributed over…
The Binomial-Stirling-Eulerian Polynomials
Kathy Q. Ji, Zhicong Lin
We introduce the binomial-Stirling-Eulerian polynomials, denoted , which encompass binomial coefficients, Eulerian numbers and two Stirling statistics: the left…
The -Eulerian Polynomials and Descent-Stirling Statistics on Permutations
Kathy Q. Ji
Carlitz and Scoville introduced the polynomials , which we refer to as the -Eulerian polynomials. These polynomials count permutations based on Eulerian-Stirl…