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Erdős problem 316

Is it true that if A⊆N∖{1}A \subseteq \mathbb{N}\setminus\{1\} is a finite set with ∑n∈A1n<2\sum_{n \in A} \frac{1}{n} < 2 then there is a partition A=A1⊔A2A=A_1 \sqcup A_2 such that ∑n∈Ai1n<1\sum_{n \in A_i} \frac{1}{n} < 1 for i=1,2i=1,2?

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3 retained statements36c6d0fef71a

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FormalConjectures/ErdosProblems/

316.lean

Retained formal statement3 of 3

This is not true if AA is a multiset, for example 2,3,3,5,5,5,52,3,3,5,5,5,5.

FormalConjectures/ErdosProblems/316.leanErdos316.erdos_316.variants.multiset17 linesExact file
∃ A,  0 ∉ A ∧    1 ∉ A ∧      (Multiset.map (fun x => 1 / x) do              let a ← A              pure ↑a).sum <          2 ∧        ∀ (A₁ A₂ : Multiset ℕ),          A = A₁ + A₂ →            1 ≤                (Multiset.map (fun x => 1 / x) do                    let a ← A₁                    pure ↑a).sum ∨              1 ≤                (Multiset.map (fun x => 1 / x) do                    let a ← A₂                    pure ↑a).sum
TextbookStatement only, no proof