5 papers
Catalan-Spitzer permutations
Richard Ehrenborg, Gábor Hetyei, Margaret Readdy
We study two classes of permutations intimately related to the visual proof of Spitzer's lemma and Huq's generalization of the Chung-Feller theorem. Both classes of permutations ar…
The Gaussian coefficient revisited
Richard Ehrenborg, Margaret A. Readdy
We give a new --analogue of the Gaussian coefficient, also known as the -binomial which, like the original -binomial , is symmetric…
Simion's type associahedron is a pulling triangulation of the Legendre polytope
Richard Ehrenborg, Gabor Hetyei, Margaret Readdy
We show that Simion's type associahedron is combinatorially equivalent to a pulling triangulation of a type root polytope called the Legendre polytope. Furthermore, we show…
Exponential Dowling structures
Richard Ehrenborg, Margaret Readdy
The notion of exponential Dowling structures is introduced, generalizing Stanley's original theory of exponential structures. Enumerative theory is developed to determine the Möbiu…
The Möbius function of partitions with restricted block size
Richard Ehrenborg, Margaret Readdy
We study filters in the partition lattice formed by restricting to partitions by type. The Möbius function is determined in terms of the easier-to-compute descent set statistics on…