2 papers
math.CO2020
Plethystic formulas for permutation enumeration
Ira M. Gessel, Yan Zhuang
We prove several general formulas for the distributions of various permutation statistics over any set of permutations whose quasisymmetric generating function is a symmetric funct…
math.CO2018
Hopping from Chebyshev polynomials to permutation statistics
Jordan O. Tirrell, Yan Zhuang
We prove various formulas which express exponential generating functions counting permutations by the peak number, valley number, double ascent number, and double descent number st…