GPT-6 Astra helps find Chair44, a 3D aperiodic monotile

Ioannis Tsiokos @ioannis_tsiokosOriginally posted 2026.09.16

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I’m releasing a new preprint presenting Chair44 (R44), a strongly aperiodic monotile for three-dimensional Euclidean space. You can find it on Zenodo, 22734468 The paper includes a Lean 4 formalization, verification code, and reproducible computational artifacts. Chair44 was found by having @OpenAI Astra use Six Birds Theory to understand what an aperiodic monotile is and look for it.