Kathy Q. Ji

collaborators

4 papers

math.CO2026

$q$ -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 SchÃ¼tzenberger and Chen, re…

math.CO2026

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…

math.CO2026

Modular Nahm sums for symmetrizable matrices of indices $(2, \dots, 2, 1)$ and $(1, \dots, 1, 2)$

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 $r \geq 2$ of indices $(2, \dots, 2, 1)$ and $(1, \dots, 1, 2)$ . Speci…

math.CO2025

Guo-Niu Han, Kathy Q. Ji, Huan Xiong

Simsun permutations, AndrÃ© I permutations and AndrÃ© II permutations are three combinatorial models for Euler numbers. It's known that the descent statistic is equidistributed ove…

q-Derivative Grammar

On the distributions of the statistics (des, maj, inv) over several classes of permutations

Modular Nahm sums for symmetrizable matrices of indices (2,…,2,1) and (1,…,1,2)

Inverse descent statistic for AndrÃ© and simsun permutations

$q$ -Derivative Grammar

Modular Nahm sums for symmetrizable matrices of indices $(2, \dots, 2, 1)$ and $(1, \dots, 1, 2)$