Generalized Bell-polynomial relation for symmetric functions

Let xm={x1,,xm}{\bf x}^m=\{x_1,\ldots,x_m\} and ym={y1,,ym}{\bf y}^m=\{y_1,\ldots,y_m\}. Let π(xm)=j=1mxj\pi({\bf x}^m)=\prod_{j=1}^m x_j, let Fn(xm)=bnBn(f1,f2,)F_n({\bf x}^m)=b_n\mathbb B_n(f_1,f_2,\ldots), where bnb_n is independent of xm{\bf x}^m and fkf_k is defined by the complete Bell-polynomial generating function. Let sim{\bf s}_i^m be the iith row of the matrix S(xm,ym){\bf S}({\bf x}^m,{\bf y}^m). Define

Vn(xm)=Fn(xm)π(xm),Un(xm,ym)=Vn(xm)i=1myimn1Vn(sim).V_n({\bf x}^m)=\frac{F_n({\bf x}^m)}{\pi({\bf x}^m)},\qquad U_n({\bf x}^m,{\bf y}^m)=V_n({\bf x}^m)-\sum_{i=1}^m y_i^{m-n-1}V_n({\bf s}_i^m).

Generalized Bell-polynomial relation. The relation

Un(xm,ym)=0,U_n({\bf x}^m,{\bf y}^m)=0,

holds for 0nm10\leq n\leq m-1. This is a proposed extension of analogous relations for particular families of symmetric polynomials; the source provides no resolution status beyond presenting it as a conjecture.

Progress summary

Solved

A 2025 preprint and a separate posted argument claim a complete proof, but neither has been independently verified.

The conjecture asserts that the stated Bell-polynomial expression vanishes for 0nm10\leq n\leq m-1. Boris Y. Rubinstein presented it as part of a broader claim for arbitrary homogeneous symmetric polynomials in an October 2025 preprint.

October 2025 claimed proof

Rubinstein’s manuscript states the relation as valid and claims the broader homogeneous-symmetric-polynomial result. The retrieved record contains no independent verification, referee report, counterexample, withdrawal, or correction.

Posted attempt

A complete proof is claimed for every symmetric homogeneous polynomial of degree n<mn<m, using cancellation of residues at the possible poles and homogeneity to force the remaining negative-degree polynomial to vanish. This argument has not been independently verified.

Current status (as of August 2026): The relation for 0nm10\leq n\leq m-1 is claimed proved by the 2025 preprint and a posted argument, but remains unverified.

Sources
Sources & referencesView supporting material

Primary source

Boris Y. Rubinstein, “A New Class of Relations for Homogeneous Symmetric Polynomials”, arXiv:2510.25749 (2025).

Solutions 1

Proof

The identity holds, more generally, for every symmetric homogeneous polynomial of degree n<mn<m.

Let SS be symmetric and homogeneous of degree nn in mm variables. Put

Dij=yixjyjxi,(si)j={xi,j=i,Dij,ji,D_{ij}=y_ix_j-y_jx_i, \qquad (s_i)_j= \begin{cases} x_i,&j=i,\\ D_{ij},&j\ne i, \end{cases}

and define

U=S(x)r=1mxri=1myimn1S(si)xijiDij.U= \frac{S(x)}{\prod_{r=1}^m x_r} - \sum_{i=1}^m \frac{y_i^{m-n-1}S(s_i)} {x_i\prod_{j\ne i}D_{ij}}.

Work over K=Q(y1,,ym)K=\mathbb Q(y_1,\ldots,y_m). As a rational function of xx, the only possible poles are the simple linear factors xix_i and DijD_{ij}.

On xi=0x_i=0, homogeneity gives

S(si)=yinS(x1,,xi1,0,xi+1,,xm),S(s_i)=y_i^nS(x_1,\ldots,x_{i-1},0,x_{i+1},\ldots,x_m), jiDij=yim1jixj.\prod_{j\ne i}D_{ij} =y_i^{m-1}\prod_{j\ne i}x_j.

Therefore the residue of the ii-th summand equals the residue of S(x)/rxrS(x)/\prod_r x_r, and their opposite signs cancel.

On Dij=0D_{ij}=0, set c=yj/yic=y_j/y_i. Then

xj=cxi,Djr=cDir(ri,j),sj=cτij(si),x_j=cx_i, \qquad D_{jr}=cD_{ir}\quad(r\ne i,j), \qquad s_j=c\,\tau_{ij}(s_i),

where τij\tau_{ij} interchanges coordinates i,ji,j. Symmetry and homogeneity imply

S(sj)=cnS(si).S(s_j)=c^nS(s_i).

Since Dji=DijD_{ji}=-D_{ij}, the ratio of the jj-th residue to the ii-th residue is

c(mn1)+n(m1)=1.-c^{(m-n-1)+n-(m-1)}=-1.

Hence these residues cancel as well.

All possible poles are removable, so

UK[x1,,xm].U\in K[x_1,\ldots,x_m].

Every term is homogeneous of degree nmn-m in xx. If 0n<m0\le n<m, that degree is negative, forcing

U=0.U=0.

Taking S=FnS=F_n, the symmetric homogeneous Bell polynomial from the conjecture, proves the desired identity for every stated m,nm,n.

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Shivam Patel ·