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Erdős problem 50

Schoenberg [Sch38] proved that the asymptotic distribution function of φ(n)/n\varphi(n)/n exists. That is, for any c[0,1]c \in [0, 1], the proportion of integers nNn \le N satisfying φ(n)/n<c\varphi(n)/n < c approaches a limit as NN \to \infty. This limit function is the cumulative distribution function of the values of φ(n)/n\varphi(n)/n.

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FormalConjectures/ErdosProblems/

50.lean

Retained formal statement1 of 3

Let ff be the asymptotic distribution function of φ(n)/n\varphi(n)/n, so that for each c[0,1]c \in [0,1], f(c)f(c) is the natural density of {n:φ(n)<cn}\{n : \varphi(n) < cn\}. Is it true that there is no xx such that the derivative f(x)f'(x) exists and is positive?

FormalConjectures/ErdosProblems/50.leanErdos50.erdos_502 linesExact file
sorry  ∀ (f : ℝ → ℝ), Erdos50.IsDistributionOfPhiRatio f → ¬∃ xSet.Icc 0 1, ∃ y > 0, HasDerivWithinAt f y (Set.Icc 0 1) x
OpenStatement only, no proof

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