A q-analog of the Seidel generation of Genocchi numbers

奇偶模式遇上Genocchi数，I：四种标号与三个双射

Parity patterns meet Genocchi numbers, I: four labelings and three bijections

本文通过四种奇偶限制排列标号超平面排列区域，建立双射并推导交织两类Genocchi数的类Seidel三角形，统一了Hetyei与Lazar-Wachs的计数结果。

The median Genocchi numbers, Q-analogues and continued fractions

The goal of this paper is twofold. First, we review the recently developed geometric approach to the combinatorics of the median Genocchi numbers. The Genocchi numbers appear in this context as Euler characteristics of the degenerate flag varieties. Second, we prove that the generating function of the Poincar\' e polynomials of the degenerate flag varieties can be written as a simple continued fraction. As an application we prove that the Poincar\' e polynomials coincide with the $q$-version of the normalized median Genocchi numbers introduced by Han and Zeng.

q-Fibonacci polynomials and q-Genocchi numbers

We show that Genocchi and Bernoulli numbers are closely related to Fibonacci polynomials and derive some q-analogues.

Gamma-positivity for a Refinement of Median Genocchi Numbers

We study the generating function of descent numbers for the permutations with descent pairs of prescribed parities, the distribution of which turns out to be a refinement of median Genocchi numbers. We prove the $γ$-positivity for the polynomial and derive the generating function for the $γ$-vectors, expressed in the form of continued fraction. We also come up with an artificial statistic that gives a $q$-analogue of the $γ$-positivity for the permutations with descents only allowed from an odd value to an odd value.

Cycles of even-odd drop permutations and continued fractions of Genocchi numbers

Recently, Lazar and Wachs (arXiv:1910.07651) showed that the (median) Genocchi numbers play a fundamental role in the study of the homogenized Linial arrangement and obtained two new permutation models (called D-permutations and E-permutations) for (median) Genocchi numbers. They further conjecture that the distributions of cycle numbers over the two models are equal. In a follow-up, Eu et al. (arXiv:2103.09130) further proved the gamma-positivity of the descent polynomials of even-odd descent permutations, which are in bijection with E-permutations by Foata's fundamental transformation. This …

On the Homogenized Linial Arrangement: Intersection Lattice and Genocchi Numbers

Hetyei recently introduced a hyperplane arrangement (called the homogenized Linial arrangement) and used the finite field method of Athanasiadis to show that its number of regions is a median Genocchi number. These numbers count a class of permutations known as Dumont derangements. Here, we take a different approach, which makes direct use of Zaslavsky's formula relating the intersection lattice of this arrangement to the number of regions. We refine Hetyei's result by obtaining a combinatorial interpretation of the Möbius function of this lattice in terms of variants of the Dumont permutation…