The Eulerian generating function of q-derangements

Generating Random Derangements

Generating involutions, derangements, and relatives by ECO

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A SYMMETRICAL q - EULERIAN IDENTITY

We find a q-analog of the following symmetrical identity involving binomial coefficients ( n m ) and Eulerian numbers An,m, due to Chung, Graham and Knuth [J. Comb., 1 (2010), 29–38]: ∑ k≥0 ( a + b k ) Ak,a−1 = ∑ k≥0 ( a + b k ) Ak,b−1. We give two proofs, using generating function and bijections, respectively.

A Mthod for Generating the Turbulent Intermittency Function

A detection method based on sensitization of a squared double differentiated signal is developed which discriminates the turbulent zones from laminar zones quite accurately. The procedure adopts a variable threshold and a variable hold time of the order of the Kolmogorov time scale. The output file so generated, includes all the information for further analysis of the turbulent signal.

On some Generalized q-Eulerian Polynomials

The (q, r)-Eulerian polynomials are the (maj−exc, fix, exc) enumerative polynomials of permutations. Using Shareshian and Wachs’ exponential generating function of these Eulerian polynomials, Chung and Graham proved two symmetrical q-Eulerian identities and asked for bijective proofs. We provide such proofs using Foata and Han’s three-variable statistic (inv−lec, pix, lec). We also prove a new ...