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Exact Local Exchange Profiles and Reconfiguration Barriers for Isosceles-Triangle-Free Grid Sets

PB
Pierre-Baptiste BorgesPosted 8 Sept 2026 · Manuscript: 27 Aug 2026
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Abstract

How can a grid point set be modified without creating an isosceles triangle? This work introduces two local profiles: points that become individually admissible after deletions, and points that can actually be added together. It establishes exact profiles around two public AlphaEvolve configurations and lower bounds on the changes required to reach another configuration of equal or greater size.

Results

eS(7) < uS(7)

On the 64 × 64 grid: 5 compatible additions, compared with 6 individually admissible points.

164 → ≤161

Every addition-and-removal path to another equally large configuration must drop to 161 points or fewer.

Method

Vertex-cover reductions, antichains of minimal masks and exact searches. On the 100 × 100 grid, the bounds at radii 6 and 7 use independently regenerated SAT instances and verified DRAT certificates. The value at radius 8 uses a directly verified witness and a separately audited exhaustive search.

Limitations

The radius-8 upper bound has no portable DRAT/LRAT proof trace. Neither configuration is claimed to be globally optimal. The reconfiguration barrier is a lower bound, not an exact value.

AI disclosure

Generative language tools, including OpenAI Codex, assisted with computational exploration, code development, literature searches and writing. The human author is responsible for the manuscript, results, references and supporting artifacts.