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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2605.08090 |
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| _version_ | 1866910202402439168 |
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| author | Kim, Jaehwan |
| author_facet | Kim, Jaehwan |
| contents | We study the rank-three lifting problem for incidence matrices of finite projective planes through residue-level determinant constraints invisible to tropical valuations alone. In residue characteristic $\neq 3$, any rank-$\le 3$ lift of the incidence matrix of a projective plane of order $q \ge 3$ forces $Ω(q^8)$ distinct admissible $2 \times 2$ zero rectangles with nontrivial residue cross-ratio. We further prove that for $q \ge 6$ no monomial rank-$\le 3$ lift exists; in particular, any putative low-rank lift must already involve nontrivial first-order corrections on valuation-0 entries. These results arise from a local analysis of $4 \times 4$ identity-pattern minors, where we derive the leading derangement equation together with its first-order companion and show that every vanished identity-pattern minor contains a cross-ratio-defective admissible rectangle. The unresolved part of the problem is therefore genuinely global: one must decide whether a rank-3 residue model, together with a compatible first-order deformation, can satisfy the full overlapping system of local residue constraints. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_08090 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Residue Constraints in the Rank-Three Lifting Problem for Projective-Plane Incidence Matrices Kim, Jaehwan Rings and Algebras Combinatorics 14T05, 15A80, 05B25 We study the rank-three lifting problem for incidence matrices of finite projective planes through residue-level determinant constraints invisible to tropical valuations alone. In residue characteristic $\neq 3$, any rank-$\le 3$ lift of the incidence matrix of a projective plane of order $q \ge 3$ forces $Ω(q^8)$ distinct admissible $2 \times 2$ zero rectangles with nontrivial residue cross-ratio. We further prove that for $q \ge 6$ no monomial rank-$\le 3$ lift exists; in particular, any putative low-rank lift must already involve nontrivial first-order corrections on valuation-0 entries. These results arise from a local analysis of $4 \times 4$ identity-pattern minors, where we derive the leading derangement equation together with its first-order companion and show that every vanished identity-pattern minor contains a cross-ratio-defective admissible rectangle. The unresolved part of the problem is therefore genuinely global: one must decide whether a rank-3 residue model, together with a compatible first-order deformation, can satisfy the full overlapping system of local residue constraints. |
| title | Residue Constraints in the Rank-Three Lifting Problem for Projective-Plane Incidence Matrices |
| topic | Rings and Algebras Combinatorics 14T05, 15A80, 05B25 |
| url | https://arxiv.org/abs/2605.08090 |