4 papers
Two refined Wilf-equivalences for patterns of length 4 and a conjecture on Dumont permutations of the first kind
Zuo-Ru Zhang, Hongkuan Zhao
We construct a bijection between -avoiding and -avoiding permutations that preserves the descent top set and the ascent top set and reverses the left-to-right order of…
Unimodality of Kazhdan--Lusztig polynomials of sparse paving matroids
Matthew H. Y. Xie, Zuo-Ru Zhang
We prove that the Kazhdan--Lusztig polynomial of a loopless sparse paving matroid is unimodal. When the rank is at least five and the corank is positive, we show that the coefficie…
The last distribution-equivalence class of mesh patterns of length 2
Zuo-Ru Zhang, Hongkuan Zhao
We prove the remaining conjectural distribution-equivalence of mesh patterns of length 2 from 2019. This completes the classification of distribution-equivalence and Wilf-equivalen…
On a question about pattern avoidance of cyclic permutations
Zuo-Ru Zhang, Hongkuan Zhao
Recently, Archer et al.\ studied cyclic permutations that avoid the decreasing pattern in one-line notation and avoid another pattern of length in all…