Department of Mathematics
Counting simsun permutations by descents
We count in the present work simsun permutations of length n by their number of descents. Properties studied include the recurrence relation and real-rootedness of the generating function of the number of n-simsun permutations with k descents. By means of generating function arguments, we show that the descent number is equidistributed over n-simsun permutations and n-André permutations. We also compute the mean and variance of the random variable Xn taking values the descent number of random n-simsun permutations, and deduce that the distribution of descents over random simsun permutations of length n satisfies a central and a local limit theorem as n → + ∞. © 2011 Springer Basel AG.
André trees, asymptotically normal, descents, simsun permutations
Source Publication Title
Annals of Combinatorics
Chow, Chak-On, and Wai Chee Shiu. "Counting simsun permutations by descents." Annals of Combinatorics 15.4 (2011): 625-635.