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I am currently working through the following paper:

Lapointe L., Lascoux A., Morse J.
Determinantal Expression and Recursion for Jack Polynomials
Electron. J. Combin. 7 (2000), Notes 1. DOI: 10.37236/1539

and I am having trouble reproducing something from that paper. This is of interest since it shows how one can express the Jack polynomial $J_{\kappa}^{(\alpha)}$ corresponding to an integer partition $\kappa$ as the determinant of an upper Hessenberg matrix (whose determinant is easy to evaluate), with the monomial symmetric polynomials as the basis.

Here is the main result I am concerned with:

Jack polynomial formula

The paper proceeds with an example showing the Jack polynomial corresponding to the integer partition $(4)$:

Jack polynomial example

My problem with the example above is in the entry $C_{\lambda\mu}$, where $\lambda$ and $\mu$ are respectively the integer partitions $(2\:2)$ and $(2\:1\:1)$. This corresponds to the $(3,3)$ entry of the determinant in the example. The paper shows that the number is $2$, but I am instead getting $4$ if I follow formula 4 in Theorem 1 that computes this number through the raising operator of a partition.

I find that $C_{\lambda\mu}=(\lambda_i-\lambda_j)n(\mu_i) n(\mu_j)=(2-0)\times 2\times 1=4$, since applying the raising operator $(R_{1,3}^{1}(2\:2\:0))^{\ast}$ (where we temporarily pad the integer partition with zeroes) does give $(2\:1\:1)$.

Did I misunderstand their Theorem 1? If, on the other hand, the formula for $C_{\lambda\mu}$ is in error, what can be done to fix it?

(Of note is that the example following Theorem 1 has a typo, which leads me to suspect that something has gotten omitted, but I have not been successful in finding an erratum for the paper, if there is one.)

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    $\begingroup$ I'm not sure that $C_{\lambda\mu}$ is well-defined. Your computation is based on $\lambda = (2,2)$ and $\mu = R^1_{13}(2,2) = (2,1,1)$ with $i = 1$ and $j=3$. But if one uses $\mu = R^1_{23}(2,2) = (2,1,1)$ with $i=2$ and $j=3$, then $C_{\lambda\mu} = (2-0)\binom{2}{2} = 2$. $\endgroup$ Commented Apr 18, 2023 at 15:27
  • $\begingroup$ Not an answer, but quite recently explicit combinatorial expressions for the Jack polynomials were worked out in the power sum basis: irif.fr/_media/users/bendali/jackpositivity.pdf $\endgroup$ Commented Apr 19, 2023 at 17:51
  • $\begingroup$ I found the Sogo article "[5]" cited as the source of Theorem 1 in hopes it could clarify what's going on, but the authors here have done quite a bit of processing to get to their statement of his work. $\endgroup$ Commented Apr 20, 2023 at 20:21
  • $\begingroup$ It's unfortunate if the $C_{\lambda\mu}$ are not quite well-determined as the paper has presented them. Just now, I tried to use their method for computing larger Jack polynomials, and it's not immediately apparent which value of $C_{\lambda\mu}$ in cases of ambiguity. $\endgroup$ Commented Apr 24, 2023 at 7:57
  • $\begingroup$ @NathanLindzey: you link is broken, can you give an alternative link? $\endgroup$ Commented Dec 1 at 19:07

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