Erdős Problem 592 #
Reference: erdosproblems.com/592
theorem
Erdos592.erdos_592
(β : Ordinal.{u})
:
β.card ≤ Cardinal.aleph0 → OrdinalCardinalRamsey (Ordinal.omega0 ^ β) (Ordinal.omega0 ^ β) 3 ↔ sorry β
Determine which countable ordinals $β$ have the property that, if $α = \omega^β$, then in any red/blue colouring of the edges of $K_α$ there is either a red $K_α$ or a blue $K_3$.