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Doron Zeilberger

Publications and source records attributed to Doron Zeilberger.

At least 127 records · Page 7Linked to original sources
arXiv2016

A Motivated Rendition of the Ellenberg-Gijswijt Gorgeous proof that the Largest Subset of $F_3^n$ with No Three-Term Arithmetic Progression is $O(c^n)$, with $c=\root 3 \of {(5589+891\,\sqrt {33})}/8=2.75510461302363300022127...$

Inspired by the Croot-Lev-Pach breakthrough, Jordan Ellenberg and Dion Gijswijt have recently amazed the combinatorial world by proving that the largest size of a subset of $F_3^n$ with no 3-term arithmetic progressions is exponentially less than the size, $3^n$ of $F_3^n$ (and, more generally, $q^n$ for $F_q^n$). Here we give a motivated, top-down, rendition of their beautiful proof, that aims to make it appreciated by a wider audience.

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arXiv2016

Using the "Freshman's Dream" to Prove Combinatorial Congruences

In a recent beautiful but technical article, William Y.C. Chen, Qing-Hu Hou, and Doron Zeilberger developed an algorithm for finding and proving congruence identities (modulo primes) of indefinite sums of many combinatorial sequences, namely those (like the Catalan and Motzkin sequences) that are expressible in terms of constant terms of powers of Laurent polynomials. We first give a leisurely exposition of their elementary but brilliant approach, and then extend it in two directions. The Laurent polynomials may be of several variables, and instead of single sums we have multiple sums. In fact we even combine these two generalizations! We conclude with some super-challenges. In this version we report that Roberto Tauraso pointed out that all our conjectured super-congruences, at the end of our article are already known, except one, for which he supplied a beautiful proof that can be found here: arXiv:1606.05543.

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arXiv2016

Integrals Involving Rudin-Shapiro Polynomials and Sketch of a Proof of Saffari's Conjecture

Continuing pioneering work of Christophe Doche and Laurent Habsieger from 2004, we develop computer algebra algorithms, implemented in Maple, for finding the (necessarily rational) generating function for any integral of products, and in particular, moments, of Rudin-Shapiro polynomials. We generate a lot of output, and confirm again a conjecture of Saffari for the asymptotics for small (and not so small) powers. We also confirm, for small powers, a related, more general, conjecture, of Hugh Montgomery. Finally, we outline a proof of Saffari's full conjecture, that we believe can be turned into a full proof. [In this version we report that Brad Rodgers has independently found a (complete!) proof of Saffari's conjecture here http://arxiv.org/abs/1606.01637] .

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arXiv2016

On the number of Singular Vector Tuples of Hyper-Cubical Tensors

Shmuel Friedland and Giorgio Ottaviani's beautiful constant term expression for the number of singular vector tuples of generic tensors is used to derive a rational generating function for these numbers, that in turn, is used to obtain an asymptotic formula for the number of such tuples for n by n by n three-dimensional tensors, and to conjecture an asymptotic formula for the general d-dimensional case. A donation of 100 dollars, in honor of the first prover, will be made to the On-line Encyclopedia of Integer Sequences.

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arXiv2016

Doron Gepner's Statistics on Words in {1,2,3} is (most probably) Asymptotically Logistic

Doron Gepner's word statistics, that came up in his research in conformal field theory, is studied and it is conjectured that its scaled limiting distribution is the Logistic distribution. We support this by proving rigorously that the scaled limits of the first twelve moments do indeed converge to those of the Logistic distribution. This is surprising, since Gepner's statistics is a natural analog of the classical statistics called the number of inversion, that is known to be asymptotically normal.

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arXiv2015

The C-finite Ansatz Meets the Holonomic Ansatz

We show how the continuous Almkvist-Zeilberger algorithm can be used to efficiently discover and prove differential equations satisfied by generating functions of sequences defined as integrals of powers of C-finite polynomial sequences (like the Chebyshev polynomials) from which one can automatically derive linear recurrences with polynomial coefficients for the sequences themselves. We fully implement this with a Maple package, CfiniteIntergal.txt .

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arXiv2015

Searching for Disjoint Covering Systems with Precisely One Repeated Modulus

A set of arithmetical sequences $$ a_1\, (\bmod{ \,\, m_1}) \quad, \quad a_2 \, (\bmod{\,\, m_2}) \quad, \quad \dots \quad , \quad a_k \, (\bmod{\,\,m_k}) \quad \quad , $$ with $$ m_1 \leq m_2 \leq \dots \leq m_k \quad \quad , $$ is called a {\it disjoint covering system} (alias {\it exact covering system}) if every positive integer belongs to {\bf exactly} one of the sequences. Mirski, Newman, Davenport and Rado famously proved that the moduli can't all be distinct. In fact the two largest moduli must be equal, i.e. $m_{k-1}=m_k$ This raises the natural question:"How close can you get to getting distinct moduli?", in other words, can you find all such systems where all the moduli are distinct except the largest, that is repeated $r$ times, for any, specific given $r$? It turns out (conjecturally, but almost certainly) that excluding the trivial case where the smallest modulus is 2, for any number of repeats $r$, there are only finitely many such systems. Marc Berger, Alexander Felzenbaum and Aviezri Fraenkel found them all for $r$ up to $9$, and Mekmamu Zeleke and Jamie Simpson extended the list for systems up to $12$ repeats. In the present article we continue the list up to $r=32$. All our systems are correct, but we did not bother to formally prove completeness, but we know for sure that the lists are complete if the largest modulus is $\leq 600$, and we are pretty sure that they are complete.

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arXiv2015

Surprising Relations Between Sums-Of-Squares of Characters of the Symmetric Group Over Two-Rowed Shapes and Over Hook Shapes

In a recent article (arXiv:1507.03499) (joint with Alon Regev) we studied sums of squares of characters Chi(L,M) of the Symmetric Group over shapes L that are two-rowed, and shapes L that are hook shapes, and M is an arbitrary shape that mostly consists of ones, and designed algorithms for closed-form evaluations of each of these. We noted (and proved) that when M is the shape with n cells consisting of 3 followed by n-3 ones, the former sum equals one half time the analogous sum over hook shapes with n+2 cells and M is the partition consisting of 3,2, followed by n-3 ones. Here we show that this is just a tip of an iceberg, and prove (alas, by purely human means) that the former sum with M consisting of all odd parts, and (possibly) a consecutive string of powers of 2, starting at 2, equals one half of the latter sum where M is replaced by a partition where all the odd parts are retained but the consecutive string of powers of 2: 2,4, ..., $2^{t-1}$ is replaced by $2^t$.

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arXiv2015

Automated Discovery and Proof of Congruence Theorems for Partial Sums of Combinatorial Sequences

Many combinatorial sequences (for example, the Catalan and Motzkin numbers) may be expressed as the constant term of $P(x)^k Q(x)$, for some Laurent polynomials $P(x)$ and $Q(x)$ in the variable $x$ with integer coefficients. Denoting such a sequence by $a_k$, we obtain a general formula that determines the congruence class, modulo $p$, of the indefinite sum $\sum_{k=0}^{rp -1} a_k$, for {\it any} prime $p$, and any positive integer $r$, as a linear combination of sequences that satisfy linear recurrence (alias difference) equations with constant coefficients. This enables us (or rather, our computers) to automatically discover and prove congruence theorems for such partial sums. Moreover, we show that in many cases, the set of the residues is finite, regardless of the prime $p$.

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arXiv2015

Explicit Expressions for the Variance and Higher Moments of the Size of a Simultaneous Core Partition and its Limiting Distribution

Jaclyn Anderson proved that if s and t are relatively prime positive integers, then there are exactly (s+t-1)!/(s!t!) partitions whose set of hook-lengths is disjoint from the set {s,t}. Drew Armstrong conjectured (and Paul Johnson, and a bit later, Victor Wang, proved) a beautiful expression for the average size, namely (s-1)(t-1)(s+t+1)/24 . In the present article, we go far beyond the average, and state absolutely certain expressions (but "officially" still conjectures) for the variance (showing in particular that it is rather large, and there is no "concentration about the mean"), and the third through the sixth moments. For the special case of (s,s+1)-core partitions, we go all the way to the 9th moment. We pose two challenges, and will be glad to donate 100 dollars each, to the OEIS foundation in honor of the first provers, regarding a "soft" and "global", yet rigorous, justification of our empirical approach, and for proving an intriguing conjecture about the limiting distribution. This version reports (thanks to Marko Thiel and Nathan Williams) that the second challenge mentioned above has been done by Paul Johnson (but not in two pages). A donation to the OEIS was made. The first challenge is still wide open.

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arXiv2015

Wilf's "Snake Oil" Method Proves an Identity in The Motzkin Triangle

We give yet-another illustration of using Herb Wilf's Snake Oil Method, by proving a certain identity between the entries of the so-called Motzkin Triangle, that arose in a recent study of enumeration of certain classes of integer partitions. We also briefly illustrate how this method can be applied to general `triangles'.

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arXiv2015

Identities in character tables of $S_n$

In the classic "Concrete Math", by Graham, Patashnik and Knuth, it is stated that "The numbers in Pascal's triangle satisfy, practically speaking, infinitely many identities, so it is not too surprising that we can find some surprising relationships by looking closely." The aim of this note is to indicate that a similar statement seems to hold for the character tables of the symmetric groups $S_n$. Just as important, it is a case-study in using a computer algebra system to prove deep identities, way beyond the ability of mere humans. This article is accomanied by a Maple pacgage, Sn, and ample output, avaialble from the webpage http://www.math.rutgers.edu/~zeilberg/mamarim/mamarimhtml/sn.html .

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arXiv2015

The number of 1...d-avoiding permutations of length d+r for SYMBOLIC d but numeric r

We use the Robinson-Schensted correspondence, followed by symbol-crunching, in order to derive explicit expressions for the quantities mentioned in the title. We follow it by number crunching, in order to compute the first terms of these sequences. As an encore, we cleverly implement Ira Gessel's celebrated determinant formula for the generating functions of these sequences, to crank out many terms. This modest tribute is dedicated to one of the greatest enumerators alive today (and definitely the most modest one!), Ira Martin Gessel, who is turning 64 years-old today

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arXiv2015

Odd-Rule Cellular Automata on the Square Grid

An "odd-rule" cellular automaton (CA) is defined by specifying a neighborhood for each cell, with the rule that a cell turns ON if it is in the neighborhood of an odd number of ON cells at the previous generation, and otherwise turns OFF. We classify all the odd-rule CAs defined by neighborhoods which are subsets of a 3 X 3 grid of square cells. There are 86 different CAs modulo trivial symmetries. When we consider only the different sequences giving the number of ON cells after n generations, the number drops to 48, two of which are the Moore and von Neumann CAs. This classification is carried out by using the "meta-algorithm" described in an earlier paper to derive the generating functions for the 86 sequences, and then removing duplicates. The fastest-growing of these CAs is neither the Fredkin nor von Neumann neighborhood, but instead is one defined by "Odd-rule" 365, which turns ON almost 75% of all possible cells.

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