Equivariant degree-one injectivity for braid-matroid Varchenko–Gelfand duals

Let cmathcalM=cmathrmBrncmathcal{M}=cmathrm{Br}_n be the braid oriented matroid, and let cmathrmVG(cmathrmBrn)i!cmathrm{VG}(cmathrm{Br}_n)^!_i denote the degree-ii component of its Koszul dual. Let cmathcalScmathrmVG(m,n1)cmathcal{S}_{cmathrm{VG}}(m,n-1) denote the corresponding cmathfrakSncmathfrak{S}_n-representation.

Braid-matroid equivariant injectivity conjecture. For all ieggeq1i eggeq 1, there exist equivariant injections

[cmathcalScmathrmVG((n1)+i,n1)]=[cmathrmVG(cmathrmBrn)i!][cmathcalScmathrmVG((n1)+i+1,n1)]=[cmathrmVG(cmathrmBrn)i+1!].[cmathcal{S}_{cmathrm{VG}}((n-1)+i,n-1)]=[cmathrm{VG}(cmathrm{Br}_n)^!_i] \hookrightarrow [cmathcal{S}_{cmathrm{VG}}((n-1)+i+1,n-1)]=[cmathrm{VG}(cmathrm{Br}_n)^!_{i+1}].

Known degree-two injections exist generally for oriented matroids, but degree-one equivariant injections need not. Computations for negleq10n egleq 10 and 1egleqiegleq91 egleq i egleq 9 support this braid-matroid claim; a proof is not supplied.

Sources & referencesView supporting material

Primary source

Ayah Almousa, Victor Reiner and Sheila Sundaram, “Koszulity, supersolvability, and Stirling representations”, arXiv:2404.10858 (2025).

Additional references

2 papers in this index state this conjecture (2003–2024). The statement above is taken from the most recent of them; the others are arXiv:math/0306013.

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