scholarly journals Combinatorics of Second Derivative: Graphical Proof of Glaisher-Crofton Identity

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Pawel Blasiak ◽  
Gérard H. E. Duchamp ◽  
Karol A. Penson
Keyword(s):  
Generating Function ◽  
Combinatorial Proof ◽  
Second Derivative ◽  
Enumerative Combinatorics ◽  
Graphical Calculus ◽  
Discrete Structures

We give a purely combinatorial proof of the Glaisher-Crofton identity which is derived from the analysis of discrete structures generated by the iterated action of the second derivative. The argument illustrates the utility of symbolic and generating function methodology of modern enumerative combinatorics. The paper is meant for nonspecialists as a gentle introduction to the field of graphical calculus and its applications in computational problems.

scholarly journals A Combinatorial Proof of an Identity for the Divisor Generating Function

10.37236/2153 ◽  
2013 ◽  
Vol 20 (2) ◽  
Author(s):  
Masanori Ando
Keyword(s):  
Generating Function ◽  
Combinatorial Proof ◽  
Divisor Function

In this paper, we give combinatorial proofs and new generalizations of $q$-series identities of Dilcher and Uchimura related to divisor function. Some interesting combinatorial results related to partition and arm-length are also presented.

scholarly journals On Walks Avoiding a Quadrant

10.37236/8019 ◽  
2019 ◽  
Vol 26 (3) ◽  
Author(s):  
Kilian Raschel ◽  
Amélie Trotignon
Keyword(s):  
Generating Function ◽  
Functional Equations ◽  
Single Equation ◽  
Convex Cones ◽  
Symmetric Convex ◽  
System Of Functional Equations ◽  
Quarter Plane ◽  
Discrete Structures ◽  
Linear Transform ◽  
Shortest Queue

Two-dimensional (random) walks in cones are very natural both in combinatorics and probability theory: they are interesting for themselves and also because they are strongly related to other discrete structures. While walks restricted to the first quadrant have been studied a lot, the case of planar, non-convex cones – equivalent to the three-quarter plane after a linear transform – has been approached only recently. In this article we develop an analytic approach to the case of walks in three quadrants. The advantage of this method is to provide uniform treatment in the study of models corresponding to different step sets. After splitting the three quadrants in two symmetric convex cones, the method is composed of three main steps: write a system of functional equations satisfied by the counting generating function, which may be simplified into one single equation under symmetry conditions; transform the functional equation into a boundary value problem; and finally solve this problem, using a concept of anti-Tutte's invariant. The result is a contour-integral expression for the generating function. Such systems of functional equations also appear in queueing theory with the famous Join-the-Shortest-Queue model, which is still an open problem in the non-symmetric case.

scholarly journals A 'Nice' Bijection for a Content Formula for Skew Semistandard Young Tableaux

10.37236/1635 ◽  
2002 ◽  
Vol 9 (1) ◽  
Author(s):  
Martin Rubey
Keyword(s):  
Generating Function ◽  
Young Tableaux ◽  
Jeu De Taquin ◽  
Enumerative Combinatorics ◽  
Bijective Proof

Based on Schützenberger's evacuation and a modification of jeu de taquin, we give a bijective proof of an identity connecting the generating function of reverse semistandard Young tableaux with bounded entries with the generating function of all semistandard Young tableaux. This solves Exercise 7.102 b of Richard Stanley's book 'Enumerative Combinatorics 2'.

scholarly journals A Triple Lacunary Generating Function for Hermite Polynomials

10.37236/1927 ◽  
2005 ◽  
Vol 12 (1) ◽  
Author(s):  
Ira M. Gessel ◽  
Pallavi Jayawant
Keyword(s):  
Orthogonal Polynomials ◽  
Generating Function ◽  
Generating Functions ◽  
Hermite Polynomials ◽  
Combinatorial Proof ◽  
Classical Orthogonal Polynomials ◽  
Combinatorial Objects ◽  
Combinatorial Interpretations

Some of the classical orthogonal polynomials such as Hermite, Laguerre, Charlier, etc. have been shown to be the generating polynomials for certain combinatorial objects. These combinatorial interpretations are used to prove new identities and generating functions involving these polynomials. In this paper we apply Foata's approach to generating functions for the Hermite polynomials to obtain a triple lacunary generating function. We define renormalized Hermite polynomials $h_n(u)$ by $$\sum_{n= 0}^\infty h_n(u) {z^n\over n!}=e^{uz+{z^2\!/2}}.$$ and give a combinatorial proof of the following generating function: $$ \sum_{n= 0}^\infty h_{3n}(u) {{z^n\over n!}}= {e^{(w-u)(3u-w)/6}\over\sqrt{1-6wz}} \sum_{n= 0}^\infty {{(6n)!\over 2^{3n}(3n)!(1-6wz)^{3n}} {z^{2n}\over(2n)!}}, $$ where $w=(1-\sqrt{1-12uz})/6z=uC(3uz)$ and $C(x)=(1-\sqrt{1-4x})/(2x)$ is the Catalan generating function. We also give an umbral proof of this generating function.

scholarly journals The Generating Function of Ternary Trees and Continued Fractions

10.37236/1079 ◽  
2006 ◽  
Vol 13 (1) ◽  
Author(s):  
Ira M. Gessel ◽  
Guoce Xin
Keyword(s):  
Generating Function ◽  
Continued Fraction ◽  
Hypergeometric Series ◽  
Combinatorial Proof ◽  
Hankel Determinant ◽  
Simple Method ◽  
Alternating Sign Matrices ◽  
Hankel Determinants ◽  
Fraction Method ◽  
Special Case

Michael Somos conjectured a relation between Hankel determinants whose entries ${1\over 2n+1}{3n\choose n}$ count ternary trees and the number of certain plane partitions and alternating sign matrices. Tamm evaluated these determinants by showing that the generating function for these entries has a continued fraction that is a special case of Gauss's continued fraction for a quotient of hypergeometric series. We give a systematic application of the continued fraction method to a number of similar Hankel determinants. We also describe a simple method for transforming determinants using the generating function for their entries. In this way we transform Somos's Hankel determinants to known determinants, and we obtain, up to a power of $3$, a Hankel determinant for the number of alternating sign matrices. We obtain a combinatorial proof, in terms of nonintersecting paths, of determinant identities involving the number of ternary trees and more general determinant identities involving the number of $r$-ary trees.

scholarly journals The Borwein Conjecture and Partitions with Prescribed Hook Differences

10.37236/1262 ◽  
1995 ◽  
Vol 3 (2) ◽  
Author(s):  
David A. Bressoud
Keyword(s):  
Generating Function ◽  
Generating Functions ◽  
Combinatorial Proof

Peter Borwein has conjectured that certain polynomials have non-negative coefficients. In this paper we look at some generalizations of this conjecture and observe how they relate to the study of generating functions for partitions with prescribed hook differences. A combinatorial proof of the generating function for partitions with prescribed hook differences is given.

scholarly journals On some Generalized $q$-Eulerian Polynomials

10.37236/2927 ◽  
2013 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhicong Lin
Keyword(s):  
Generating Function ◽  
Recurrence Formula ◽  
Combinatorial Proof ◽  
Eulerian Polynomials ◽  
Exponential Generating Function

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 recurrence formula for the $(q,r)$-Eulerian polynomials and study a $q$-analogue of Chung and Graham's restricted descent polynomials. In particular, we obtain a generalized symmetrical identity for these restricted $q$-Eulerian polynomials with a combinatorial proof.

scholarly journals CONGRUENCES MODULO SQUARES OF PRIMES FOR FU'S k DOTS BRACELET PARTITIONS

2013 ◽  
Vol 09 (04) ◽  
pp. 939-943 ◽  
Author(s):  
CRISTIAN-SILVIU RADU ◽  
JAMES A. SELLERS
Keyword(s):  
Positive Integer ◽  
Generating Function ◽  
Infinite Family ◽  
Combinatorial Proof ◽  
Combinatorial Approach ◽  
Powers Of 2 ◽  
The Family ◽  
Fixed Positive Integer ◽  
Congruence Properties

In 2007, Andrews and Paule introduced the family of functions Δk(n) which enumerate the number of broken k-diamond partitions for a fixed positive integer k. In that paper, Andrews and Paule proved that, for all n ≥ 0, Δ1(2n+1) ≡ 0 (mod 3) using a standard generating function argument. Soon after, Shishuo Fu provided a combinatorial proof of this same congruence. Fu also utilized this combinatorial approach to naturally define a generalization of broken k-diamond partitions which he called k dots bracelet partitions. He denoted the number of k dots bracelet partitions of n by 𝔅k(n) and proved various congruence properties for these functions modulo primes and modulo powers of 2. In this note, we extend the set of congruences proven by Fu by proving the following congruences: For all n ≥ 0, [Formula: see text] We also conjecture an infinite family of congruences modulo powers of 7 which are satisfied by the function 𝔅7.

scholarly journals Enumeration of derangements with descents in prescribed positions

2009 ◽  
Vol DMTCS Proceedings vol. AK,... (Proceedings) ◽  
Author(s):  
Niklas Eriksen ◽  
Ragnar Freij ◽  
Johan Wästlund
Keyword(s):  
Fixed Point ◽  
Generating Function ◽  
Combinatorial Proof ◽  
Explicit Formulas ◽  
International Audience ◽  
Special Case

International audience We enumerate derangements with descents in prescribed positions. A generating function was given by Guo-Niu Han and Guoce Xin in 2007. We give a combinatorial proof of this result, and derive several explicit formulas. To this end, we consider fixed point $\lambda$-coloured permutations, which are easily enumerated. Several formulae regarding these numbers are given, as well as a generalisation of Euler's difference tables. We also prove that except in a trivial special case, if a permutation $\pi$ is chosen uniformly among all permutations on $n$ elements, the events that $\pi$ has descents in a set $S$ of positions, and that $\pi$ is a derangement, are positively correlated.

scholarly journals Enumeration of Derangements with Descents in Prescribed Positions

10.37236/121 ◽  
2009 ◽  
Vol 16 (1) ◽  
Author(s):  
Niklas Eriksen ◽  
Ragnar Freij ◽  
Johan Wästlund
Keyword(s):  
Fixed Point ◽  
Generating Function ◽  
Combinatorial Proof ◽  
Explicit Formulas ◽  
Special Case

We enumerate derangements with descents in prescribed positions. A generating function was given by Guo-Niu Han and Guoce Xin in 2007. We give a combinatorial proof of this result, and derive several explicit formulas. To this end, we consider fixed point $\lambda$-coloured permutations, which are easily enumerated. Several formulae regarding these numbers are given, as well as a generalisation of Euler's difference tables. We also prove that except in a trivial special case, if a permutation $\pi$ is chosen uniformly among all permutations on $n$ elements, the events that $\pi$ has descents in a set $S$ of positions, and that $\pi$ is a derangement, are positively correlated.

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