arXiv subjects
Publications and source records attributed to Doron Zeilberger.
The problems of enumerating lattice walks, with an arbitrary finite set of allowed steps, both in one and two dimensions, where one must always stay in the non-negative half-line and quarter-plane respectively, are used, as case studies, to illustrate the `naive' methodology of guess-and-check, where rigorous proofs are possible, but not worth the trouble. We argue that this is a metaphor for future math.
We present an empirical-yet-rigorous approach for solving a wide class of functional equations, thereby automating many results that previously required considerable human ingenuity and human labor.
In this article, dedicated with admiration and gratitude to guru Neil Sloane on his 75-th birthday, we observe that the generating functions for multi-set permutations that do not contain an increasing subsequence of length d, and where every letter appears the same number of times, say r, are always D-finite, (for every d and every r), and we actually crank out the first few terms of quite a few of them, many of whom are not yet in the OEIS. We also state a conjectured asymptotic formula for these sequences, that reduces to Amitai Regev's famous formula when r=1, and pledge a 100 dollar donation to the OEIS in honor of the first one to prove our conjecture. We pledge another 100 dollars for extending Ira Gessel's spectacular Bessel determinant, from the r=1 case to general r.
The beautiful theory of statistical gambling, started by Dubins and Savage (for subfair games) and continued by Kelly and Breiman (for superfair games) has mostly been studied under the unrealistic assumption that we live in a continuous world, that money is indefinitely divisible, and that our life is indefinitely long. Here we study these fascinating problems from a purely discrete, finitistic, and computational, viewpoint, using Both Symbol-Crunching and Number-Crunching (and simulation just for checking purposes).
Recently, Bill Chen, together with his disciples Alvin Dai and Robin Zhou, discovered, and very elegantly proved, an algebraic equation satisfied by the generating function enumerating 123-avoiding words with two occurrences of each of 1, ..., n. Inspired by this result, we present an algorithm for finding such an algebraic equation for the ordinary generating function enumerating 123-avoiding words with exactly r occurrences of each of 1, ... n for any positive integer r, thereby proving that they are algebraic and not merely D-finite (a fact that is promised by WZ theory). Our algorithm consists of presenting an algebraic enumeration scheme, combined with the Buchberger algorithm
Once upon a time there was an esoteric and specialized notion, called "size of the Durfee square", of interest to at most 100 specialists in the whole world. Then it was kissed by a prince called Jorge Hirsch, and became the famous (and to quite a few people, infamous) h-index, of interest to every scientist, and scholar, since it tells you how productive a scientist (or scholar) you are! When Rodney Canfield, Sylvie Corteel, and Carla Savage wrote their beautiful 1998 article proving, rigorously, by a very deep and intricate analysis, the asymptotic normality of the random variable "size of Durfee square" defined on integer-partitions of n (as n goes to infinity), with precise asymptotics for the mean and variance, they did not dream that one day their result should be of interest to everyone who has ever published a paper. However Canfield et. al. had to work really hard to prove their deep result. Here we take an "empirical" shortcut, that proves the same thing much faster (modulo routine number- and symbol- crunching). More importantly, the empirical methodology should be useful in many other cases where rigorous proofs are either too hard, or not worth the trouble!
This short "education note" was inspired by Zvi Artstein's masterpiece Mathematics and the Real World, the Remarkable Role of Evolution in the Making of Mathematics (p. 53, and p. 400)
Using the Morris-Selberg Constant Term Identity, I sketch a proof of a recent conjecture by Karola Meszaros and Alejandro Morales, that I believe could be easily made fully rigorous by a sufficiently skilled and, sufficiently interested, analyst. This conjecture is an analog to the root system $D_n$ of a conjecture made in 1998 by Clara Chan, the late David P. Robbins, and David Yuen, that I proved immediately after, also using the Morris identity.
This short tribute to the guru of Enumerative and Algebraic Combinatorics started out when one the authors(DZ) attended the Stanely@70 conference, that took place at the same time as the preliminary stage of the 2014 World Cup. It states a surprising application of an analog of Richard Stanley's famous theorem about the enumeration of magic squares to the enumeration of possible outcomes in a World Cup Group.
Joshua Cooper and Mark Walters initiated the subject that we call here Enumerative Geometric Genealogy, (and that lead to the hard-to-count OEIS sequence A140468) but they did not realize the broader impact of their research to the population explosion of a certain far-away planet, whose inhabitants are much smarter, and more civilized, than we are.
Roger Apery's seminal method for proving irrationality is "turned on its head" and taught to computers, enabling a one second redux of the original proof of zeta(3), and many new irrationality proofs of many new constants, alas, none of them is both famous and not-yet-proved-irrational.
In this case-study in computer-human collaboration, we develop, implement, and execute symbolic-computational algorithms for the automatic discovery and proof of explicit expressions for the expectation, variance, and higher moments of a large class of natural combinatorial statistics defined on Catalan-counted objects, enabling, inter-alia, to prove that they are not asymptotically normal. In particular, we reproduce in 0.12 seconds results of Miklos Bona, and derive far deeper results, way beyond the scope of humans, concerning higher moments of the random variable "number of occurrences of a pattern" in the set of 132-avoiding permutations for all patterns of length 2 and 3, and, more impressively, explicit expressions for the averages for all patterns of lengths up to 10. The ample output inspired us to make an intriguing conjecture concerning the number of so-called Bona classes, and we pledge to donate 100 dollars to the OEIS Foundation in honor of the prover (or disprover).
I conjecture a certain explicit determinant evaluation, whose proof would imply the solution of certain enumeration problem that I have been working on, and that I find interesting. I am pledging \$500 to the OEIS Foundation (in honor of the prover!) for a proof, and \$50 (in honor of the disprover)
I describe an empirical-yet-rigorous, algorithm, based on Riordan's rook polynomials and the so-called C-finite ansatz, fully implemented in the accompanying Maple package (http://www.math.rutgers.edu/~zeilberg/tokhniot/MENAGES ), MENAGES, that reproduces in a few seconds, rigorously-proved enumeration theorems on permutations with restricted positions, previously proved by quite a few illustrious human mathematicians, and that can go far beyond any human attempts.
We study statistical properties of the random variables $X_σ(π)$, the number of occurrences of the pattern $σ$ in the permutation $π$. We present two contrasting approaches to this problem: traditional probability theory and the ``less traditional'' computational approach. Through the perspective of the first one, we prove that for any pair of patterns $σ$ and $τ$, the random variables $X_σ$ and $X_τ$ are jointly asymptotically normal (when the permutation is chosen from $S_{n}$). From the other perspective, we develop algorithms that can show asymptotic normality and joint asymptotic normality (up to a point) and derive explicit formulas for quite a few moments and mixed moments empirically, yet rigorously. The computational approach can also be extended to the case where permutations are drawn from a set of pattern avoiders to produce many empirical moments and mixed moments. This data suggests that some random variables are not asymptotically normal in this setting.
This article is a sequel to a recent article by Eric Rowland and Reem Yassawi, presenting yet another approach to the fast determination of congruence properties of `famous' combinatorial sequences. The present approach can be taught to a computer, and our beloved servant, Shalosh B. Ekhad, was able to generate many new theorems, for famous sequences, of course, but also for many obscure ones!
We show how to extend the Karolyi-Nagy beautiful proof of the Zeilberger-Bressoud q-Dyson theorem, (first proved by Zeilberger and Bressoud in 1985, and originally conjectured by George Andrews in 1975), that states that the constant term of a certain Laurent polynomial equals the q-multinomial coefficient, how to evaluate any other specific coefficient. The algorithm implies that any such coefficient is always a certain rational function (that the algorithm finds) times the q-multinomial coefficient.
When Mike Hirschhorn showed us his lovely gem, that gives the simplest-to-date proof of Ramanujan's famous result that p(11n+6) is divisible by 11, we realized that his amazing method can be extended, and taught to a computer, and can prove even deeper identities. We would have done much more if not for the existence of Silviu Radu's powerful algorithm that handle any Ramanujan type congruence for any modular form (of a very general type), but it is still nice to know that in order to prove such simply stated results, that can be explained to a seven-year-old, one does not need the intimidating edifice of the "web of modularity", that Ramanujan never mastered, and probably would not have liked.