Erdős Problem 221 — qed.bot Claims, announcements and changes recorded against Erdős Problem 221. https://qed.bot/feeds/s/erdos-221.xml 2026-01-31T00:00:00Z qed.bot Erdős Problem 221 — full (Aristotle) urn:qed:8482b5cc4fdb 2026-01-31T00:00:00Z Ruzsa (1972) + van Doorn (2025). Autonomy A1, evidence V1, fidelity F2.