Skip to main content
MathOverflow
Ira Gessel's user avatar
Ira Gessel's user avatar
Ira Gessel's user avatar
Ira Gessel
  • Member for 14 years, 1 month
  • Last seen this week
  • Brandeis University, Waltham, MA, United States
Profile Activity

822 Actions

All Accepts Posts Badges Comments Revisions Reviews Suggestions
answered
On the polynomial $\sum_{k=0}^n\binom{n}{k}(-1)^kX^{k(n-k)}$
comment
Matrix continued fractions
For an application of Motzkin paths with matrix weights, see Paul Monsky, Generating Functions Attached to some Infinite Matrices, Electronic J. Combinatorics, Volume 18, Issue 1 (2011), Paper #P5, combinatorics.org/ojs/index.php/eljc/article/view/v18i1p5.
awarded
 Necromancer
comment
Who proved the reflection principle in random walks and Brownian motion?
See webspace.ship.edu/msrenault/ballotproblem/… and webspace.ship.edu/msrenault/ballotproblem.
revised
Computing the relative class group (with Galois action) of relatively large cyclotomic groups
deleted 1 character in body
revised
What is the number of achiral color patterns for a row of n colors containing k different colors?
deleted 4 characters in body
comment
Illustrating mathematics with wysiwyg tools
I use EazyDraw (for Mac), eazydraw.com, using LaTeXiT for formulas (chachatelier.fr/latexit/latexit-home.php?lang=en).
comment
Sum of products of binomials
You can use Petkovšek's algorithm (en.wikipedia.org/wiki/Petkovšek%27s_algorithm) to prove that there is no closed form for the sum.
comment
Rational Binomial Identity
The identity is a special case of Vandermonde's theorem.
revised
What is $\int_{0}^{z} e^{-a^{2} x^{2}} {\rm erf}(bx)\, dx$?
added 16 characters in body; edited title
revised
Examples of theorems misapplied to non-mathematical contexts
added 18 characters in body
revised
Product of hypergeometric functions/Jacobi Polynomials
added 5 characters in body
comment
What is the number of achiral color patterns for a row of n colors containing k different colors?
@MaxAlekseyev I don't think so.
comment
Counting labeled triangle-free graphs on $n$ vertices
It's very unlikely that there's a reasonable formula.
awarded
 Guru
revised
What is the number of achiral color patterns for a row of n colors containing k different colors?
deleted 1 character in body
awarded
 Enlightened
revised
What is the number of achiral color patterns for a row of n colors containing k different colors?
deleted 66 characters in body
revised
What is the number of achiral color patterns for a row of n colors containing k different colors?
deleted 66 characters in body
revised
What is the number of achiral color patterns for a row of n colors containing k different colors?
deleted 66 characters in body
1
…
22 23
24
25 26
…
42