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Erdős problem 596

Erdős Problem 596 (Erdős–Hajnal, [Er87]). For which graph pairs (G1,G2)(G_1, G_2) is it true that

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9 retained statements2415f78e850a

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FormalConjectures/ErdosProblems/

596.lean

Retained formal statement7 of 9

Whether (K4,K3)(K_4, K_3) is Erdős–Hajnal exceptional is precisely the content of Erdős Problem 595. The finite Ramsey property holds (Folkman 1970, Nešetřil–Rödl [NeRo75]); the open part is whether every K4K_4-free graph is a countable union of triangle-free graphs.

FormalConjectures/ErdosProblems/596.leanErdos596.erdos_596.variants.K4_K3_exceptional_iff1 lineExact file
True ↔ (SimpleGraph.completeGraph (Fin 4)).IsErdosHajnalExceptional (SimpleGraph.completeGraph (Fin 3))
OpenStatement only, no proof

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