What is the value of this finite sum?

  • Thread starter Thread starter Pere Callahan
  • Start date Start date
  • Tags Tags
    Finite Sum Value
Pere Callahan
Messages
582
Reaction score
1
Hi,

I came across a somewhat unwieldy sum which I do not know how to manipulate any further. I suspect it might have something to do with a hypergeometric series, but I am not sufficiently familar with those series to be able to just see how it might be related to them.

The sum in question is

\sum_{1\leq r_1< r_2 < \dots < r_n \leq m}{\frac{ (k-1)!(k-2r_1)!(k-2r_2+1)! \dots (k-2r_{n-1}+n-2)!(k-2r_n+n-1)! }{ (k-2r_1+1)!(k-2r_2+2)! \dots (k-2r_{n-1}+n-1)!(k-2r_n+n)! }}

where k is some non-negative integer, 0\leq n \leq k. m is defined by

m=\left\lfloor\frac{k+n}{2}\right\rfloor \geq n.

Do you know of any books where I could look up things like that?

Any help is greatly appreciated.

-Pere
 
Last edited:
Physics news on Phys.org
Thanks. A=B seems to be an intersting book, I hadn't heard of it before.
 
##\textbf{Exercise 10}:## I came across the following solution online: Questions: 1. When the author states in "that ring (not sure if he is referring to ##R## or ##R/\mathfrak{p}##, but I am guessing the later) ##x_n x_{n+1}=0## for all odd $n$ and ##x_{n+1}## is invertible, so that ##x_n=0##" 2. How does ##x_nx_{n+1}=0## implies that ##x_{n+1}## is invertible and ##x_n=0##. I mean if the quotient ring ##R/\mathfrak{p}## is an integral domain, and ##x_{n+1}## is invertible then...
The following are taken from the two sources, 1) from this online page and the book An Introduction to Module Theory by: Ibrahim Assem, Flavio U. Coelho. In the Abelian Categories chapter in the module theory text on page 157, right after presenting IV.2.21 Definition, the authors states "Image and coimage may or may not exist, but if they do, then they are unique up to isomorphism (because so are kernels and cokernels). Also in the reference url page above, the authors present two...
When decomposing a representation ##\rho## of a finite group ##G## into irreducible representations, we can find the number of times the representation contains a particular irrep ##\rho_0## through the character inner product $$ \langle \chi, \chi_0\rangle = \frac{1}{|G|} \sum_{g\in G} \chi(g) \chi_0(g)^*$$ where ##\chi## and ##\chi_0## are the characters of ##\rho## and ##\rho_0##, respectively. Since all group elements in the same conjugacy class have the same characters, this may be...
Back
Top