First-order nonvanishing obstruction for rank-three incidence lifts

From papers

Let Π\Pi be a projective plane of order qq, let UU be a rank-33 residue zero-pattern model satisfying the identity-pattern minor constraints, and let TUT_U denote its tangent space. First-order nonvanishing obstruction. For sufficiently large qq, no such model admits a tangent direction VTUV\in T_U satisfying

Vp0for every incidence p.V_{p\ell}\neq 0\qquad\text{for every incidence }p\in\ell.

Equivalently, any putative rank-3\leq 3 lift of the incidence matrix I(Π)I(\Pi) should force at least one incidence entry to acquire valuation at least 22. This would strengthen the paper's established first-order obstructions by ruling out a tangent direction that is nonzero on every incidence position; the global claim remains open.

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Sources & referencesView supporting material

Primary source

Jaehwan Kim, “Residue Constraints in the Rank-Three Lifting Problem for Projective-Plane Incidence Matrices”, arXiv:2605.08090 (2026).

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