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Erdős problem 303

Is it true that in any finite colouring of the integers there exists a monochromatic solution to 1a=1b+1c\frac 1 a = \frac 1 b + \frac 1 c with distinct a,b,ca, b, c?

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FormalConjectures/ErdosProblems/

303.lean

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Is it true that in any finite colouring of the integers there exists a monochromatic solution to 1a=1b+1c\frac 1 a = \frac 1 b + \frac 1 c with distinct a,b,ca, b, c?

This is true, as proved by Brown and Rödl [BrRo91].

This was formalized in Lean by Yuan using Seed-Prover.

FormalConjectures/ErdosProblems/303.leanErdos303.erdos_3033 linesExact file
True  ∀ (𝓒 : ℤ → ℤ),    (Set.range 𝓒).Finite → ∃ a b c, [a, b, c, 0].Nodup ∧ 1 / ↑a = 1 / ↑b + 1 / ↑c ∧ (𝓒 '' {a, b, c}).Subsingleton
SolvedProof has a holelean4external proof

The proof uses `sorry`: part of the argument is written but not proved. Lean accepts the file; it does not accept the theorem.

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