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Erdős problem 282

Let ANA\subseteq \mathbb{N} be an infinite set and consider the following greedy algorithm for a rational x(0,1)x\in (0,1): choose the minimal nAn\in A such that n1/xn\geq 1/x and repeat with xx replaced by x1nx-\frac{1}{n}. If this terminates after finitely many steps then this produces a representation of xx as the sum of distinct unit fractions with denominators from AA.

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FormalConjectures/ErdosProblems/

282.lean

Retained formal statement1 of 8

Let ANA\subseteq \mathbb{N} be an infinite set and consider the following greedy algorithm for a rational x(0,1)x\in (0,1): choose the minimal nAn\in A such that n1/xn\geq 1/x and repeat with xx replaced by x1nx-\frac{1}{n}. If this terminates after finitely many steps then this produces a representation of xx as the sum of distinct unit fractions with denominators from AA.

Does this process always terminate if xx has odd denominator and AA is the set of odd numbers?

FormalConjectures/ErdosProblems/282.leanErdos282.erdos_2821 lineExact file
∀ {x : ℚ}, xSet.Ioo 0 1 → Odd x.denErdos282.greedyUnitFractionRem {n | Odd n} x =ᶠ[Filter.atTop] 0
OpenStatement only, no proof

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