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Erdős problem 1167

Erdős Problem 1167. Let r2r \geq 2 be finite, γ2\gamma \geq 2, and λ\lambda be an infinite cardinal. Let κα\kappa_\alpha be cardinals for all α<γ\alpha < \gamma. Is it true that 2λ(κα+1)α<γr+12^\lambda \to (\kappa_\alpha + 1)_{\alpha < \gamma}^{r+1} implies λ(κα)α<γr?\lambda \to (\kappa_\alpha)_{\alpha < \gamma}^r? Here ++ means cardinal addition, so that κα+1=κα\kappa_\alpha + 1 = \kappa_\alpha if κα\kappa_\alpha is infinite.

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8 retained statements2415f78e850a

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FormalConjectures/ErdosProblems/

1167.lean

Retained formal statement5 of 8

Finite-target case. When all κα\kappa_\alpha are finite, κα+1\kappa_\alpha + 1 is the ordinary natural-number successor. Special case of erdos_1167.

FormalConjectures/ErdosProblems/1167.leanErdos1167.erdos_1167.variants.finite_targets9 linesExact file
∀ (r : ℕ),  2 ≤ r    ∀ (lam : Cardinal.{u}),      Cardinal.aleph0lam        ∀ (γ : Ordinal.{u}),          2 ≤ γ →            ∀ (n : γ.ToType → ℕ),              (Combinatorics.cardinalPartitionRel (2 ^ lam) (r + 1) γ fun α => ↑(n α) + 1) →                Combinatorics.cardinalPartitionRel lam r γ fun α => ↑(n α)
OpenStatement only, no proof

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