{"schema":"vela.problem-packet.v0.1","problem":196,"statement":"Must every permutation of $\\mathbb{N}$ contain a monotone 4-term arithmetic progression? In other words, given a permutation $x$ of $\\mathbb{N}$ must there be indices with either $i<j<k<l$ or $i>j&#62;k&#62;l$ such that $x_i,x_j,x_k,x_l$ are an arithmetic progression?","status":"open","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)"}