A central limit theorem for descents of a Mallows permutation and its inverse
arXiv:2005.09802 · doi:10.1214/21-AIHP1167
Abstract
This paper studies the asymptotic distribution of descents $\des(w)$ in a permutation , and its inverse, distributed according to the Mallows measure. The Mallows measure is a non-uniform probability measure on permutations introduced to study ranked data. Under this measure, permutations are weighted according to the number of inversions they contain, with the weighting controlled by a parameter . The main results are a Berry-Esseen theorem for $\des(w)+\des(w^{-1})$ as well as a joint central limit theorem for $(\des(w),\des(w^{-1}))$ to a bivariate normal with a non-trivial correlation depending on . The proof uses Stein's method with size-bias coupling along with a regenerative process associated to the Mallows measure.
v2 some added references and minor changes to introduction. 35 pages, 1 figure, 1 table. Comments are welcome!