{"schema":"vela.problem-packet.v0.1","problem":192,"statement":"Let $A=\\{a_1,a_2,\\ldots\\}\\subset \\mathbb{R}^d$ be an infinite sequence such that $a_{i+1}-a_i$ is a positive unit vector (i.e. is of the form $(0,0,\\ldots,1,0,\\ldots,0)$). For which $d$ must $A$ contain a three-term arithmetic progression?","status":"solved","seam":"raw","closureRoutes":[],"obligations":[],"attestations":[],"attempts":[],"velaLean":[],"oeis":[],"generated_note":"derived view; the signed event log is the source of truth (vela check / vela reproduce)"}