Sorting conjecture for stable symmetric-group representations

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Let λ\lambda and μ\mu be partitions. Rearrange all their parts in weakly decreasing order as

λ∪μ=(ν1,ν2,ν3,…).\lambda\cup\mu=(\nu_1,\nu_2,\nu_3,\ldots).

Define sort⁡1(λ,μ)=(ν1,ν3,ν5,…)\operatorname{sort}_1(\lambda,\mu)=(\nu_1,\nu_3,\nu_5,\ldots) and sort⁡2(λ,μ)=(ν2,ν4,ν6,…)\operatorname{sort}_2(\lambda,\mu)=(\nu_2,\nu_4,\nu_6,\ldots). In Rep⁡(S∞)\operatorname{Rep}(S_{\infty}), let Vλ[∞]V_{\lambda[\infty]} denote the simple object indexed by λ\lambda, and order the Grothendieck ring coefficientwise.

Sorting conjecture.

Vsort⁡1(λ,μ)[∞]⊗Vsort⁡2(λ,μ)[∞]≥Vλ[∞]⊗Vμ[∞].V_{\operatorname{sort}_1(\lambda,\mu)[\infty]}\otimes V_{\operatorname{sort}_2(\lambda,\mu)[\infty]} \geq V_{\lambda[\infty]}\otimes V_{\mu[\infty]}.

This generalizes the cited sorting conjecture for tensor-product multiplicities. Its validity would give a broad family of coefficientwise inequalities in the stable representation category; the paper does not establish it in general.

References

Primary source

Tao Gui, “Conjectures on the reduced Kronecker coefficients”, arXiv:2210.14668 (2026).

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