{"schema":"vela.problem-packet.v0.1","problem":1128,"statement":"Let $A,B,C$ be three sets of cardinality $\\aleph_1$. Is it true that, in any $2$-colouring of $A\\times B\\times C$, there must exist $A_1\\subset A$, $B_1\\subset B$, $C_1\\subset C$, all of cardinality $\\aleph_0$, such that $A_1\\times B_1\\times C_1$ is monochromatic?","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)"}