Homogeneous-polynomial extension of the generalized relation

Let xm={x1,,xm}{\bf x}^m=\{x_1,\ldots,x_m\} and let 1m{\bf 1}^m denote the mm-tuple all of whose entries are 11. Let Un(xm,ym)U_n({\bf x}^m,{\bf y}^m) be the function defined from the symmetric polynomials FnF_n and the rows of S(xm,ym){\bf S}({\bf x}^m,{\bf y}^m). Homogeneous-polynomial extension. For nmn\geq m, specializing ym=1m{\bf y}^m={\bf 1}^m gives a homogeneous symmetric polynomial Znm(xm)Z_{n-m}({\bf x}^m) of degree nmn-m:

Un(xm,1m)=Znm(xm),nm.U_n({\bf x}^m,{\bf 1}^m)=Z_{n-m}({\bf x}^m),\qquad n\geq m.

The claim extends the preceding relation beyond n=m1n=m-1 and asserts polynomiality after the specialization; the source gives no evidence resolving it.

Progress summary

Solved

A 2025 preprint claims the extension is valid in full generality, and a posted complete-proof attempt is unverified.

The problem asks whether specializing the generalized relation at ym=1m{\bf y}^m={\bf 1}^m always produces a homogeneous symmetric polynomial for nmn\ge m. Boris Y. Rubinstein's 2025 preprint claims a broader result: the underlying relations hold for every homogeneous symmetric polynomial.

October 2025 claimed generalization

Rubinstein claims that the relations are valid for arbitrary homogeneous symmetric polynomials, which would imply the stated extension for the specified family FnF_n. The retrieved record contains no independent verification.

Posted attempt

A complete proof attempt argues that all possible poles at xi=0x_i=0 and xi=xjx_i=x_j cancel by symmetry, leaving a homogeneous symmetric polynomial of degree nmn-m. This attempt has not been independently verified.

Current status (as of August 2026): A 2025 preprint claims the extension, but no independent verification is recorded, so the claim remains unsettled.

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 asserted extension holds for every symmetric homogeneous polynomial, not only for the specified Bell-polynomial family.

Let SS be any symmetric homogeneous polynomial of degree nn in mm variables, and specialize y1==ym=1y_1=\cdots=y_m=1. Put

(si)j={xi,j=i,xjxi,ji.(s_i)_j= \begin{cases} x_i,&j=i,\\ x_j-x_i,&j\ne i. \end{cases}

The rational expression in the conjecture becomes

U(x,1)=S(x)r=1mxri=1mS(si)xiji(xjxi).U(x,\mathbf1) = \frac{S(x)}{\prod_{r=1}^m x_r} - \sum_{i=1}^m \frac{S(s_i)} {x_i\prod_{j\ne i}(x_j-x_i)}.

Its only possible polar factors are the distinct irreducible linear forms

xi,xjxi.x_i,\qquad x_j-x_i.

When xi=0x_i=0, the vector sis_i agrees with xx with its ii-th coordinate set to zero. Consequently the residue of the ii-th summand is

S(x1,,xi1,0,xi+1,,xm)jixj,\frac{S(x_1,\ldots,x_{i-1},0,x_{i+1},\ldots,x_m)} {\prod_{j\ne i}x_j},

which exactly cancels the residue of S(x)/rxrS(x)/\prod_r x_r.

When xi=xjx_i=x_j, the vectors sis_i and sjs_j differ only by interchanging coordinates ii and jj. Symmetry gives

S(si)=S(sj).S(s_i)=S(s_j).

All other denominator factors coincide, whereas the singular factors satisfy

xjxi=(xixj).x_j-x_i=-(x_i-x_j).

Thus the residues of the ii-th and jj-th summands cancel.

Every possible pole is therefore removable, proving

U(x,1)Q[x1,,xm].U(x,\mathbf1)\in\mathbb Q[x_1,\ldots,x_m].

Each summand is homogeneous of degree nmn-m, so the resulting polynomial is homogeneous of degree nmn-m, or zero. Finally, every permutation of the xx-coordinates permutes the summands, while symmetry of SS preserves their numerators. Hence U(x,1)U(x,\mathbf1) is symmetric.

Taking S=FnS=F_n and nmn\ge m gives exactly the conjectured homogeneous symmetric polynomial ZnmZ_{n-m}.

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