Erdős problem 602
Does every almost-disjoint family of countably infinite sets whose pairwise intersections all have size ≠ 1 have Property B?
Sources
FormalConjectures/ErdosProblems/
602.lean
Retained formal statement
Unique index set.
If the index set has exactly one element (i.e., [Unique I]), then Property B holds: any 2-colouring that makes the single set A (default : I) non-monochromatic works. This follows from the single-set case.
∀ {α : Type u_1} (I : Type u_2) [Unique I] (A : I → Set α), (∀ (i : I), (A i).Infinite) → Erdos602.HasPropertyB I ATextbookStatement only, no proof