{"schema":"vela.problem-packet.v0.1","problem":1091,"statement":"Let $G$ be a $K_4$-free graph with chromatic number $4$. Must $G$ contain an odd cycle with at least two diagonals?More generally, is there some $f(r)\\to \\infty$ such that every graph with chromatic number $4$, in which every subgraph on $\\leq r$ vertices has chromatic number $\\leq 3$, contains an odd cycle with at least $f(r)$ diagonals?","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)"}