Two-barrier Ore-degree conjecture for direct-sum matchings

From papers

Let VV be an nn-dimensional vector space over the field with qq elements, and let [Vk]\genfrac{[}{]}{0pt}{}{V}{k} denote the set of kk-dimensional subspaces of VV. For a family F[Vk]\mathcal F\subsetneq\genfrac{[}{]}{0pt}{}{V}{k}, let σk,q(F)\sigma_{k,q}(\mathcal F) be its projective Ore-degree and let ν(F)\nu_{\oplus}(\mathcal F) be its maximum direct-sum matching size. For integers k2k\ge2, s2s\ge2, and nksn\ge ks, define Dq(n,k,s1)D_q(n,k,s-1) as in the paper.

Two-barrier Ore-degree conjecture. If

σk,q(F)>max{[k1]qDq(n,k,s1),  [max{0,(s+1)kn1}1]q[sk2k1]q},\sigma_{k,q}(\mathcal F)>\max\left\{\genfrac{[}{]}{0pt}{}{k}{1}_{q}D_q(n,k,s-1),\;\genfrac{[}{]}{0pt}{}{\max\{0,(s+1)k-n-1\}}{1}_{q}\genfrac{[}{]}{0pt}{}{sk-2}{k-1}_{q}\right\},

then ν(F)s\nu_{\oplus}(\mathcal F)\ge s.

This corrects the single-threshold formulation, which fails in the full range because both the linear-stability obstruction and the subspace-clique obstruction can control the Ore-degree threshold.

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Sources & referencesView supporting material

Primary source

Mengyu Cao, Mei Lu, Xuyang Yan and Haixiang Zhang, “Projective Ore-Degree Conditions for Intersection Theorems in Vector Spaces”, arXiv:2607.25598 (2026).

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