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Handelman's Question on integrability of h(x)/h(2x) for log-convex h with lim h(n)^{1/n} = 1

Determine whether, for a log-convex function h:(0,∞)→(0,∞) that is integrable on (0,∞) and satisfies lim_{n→∞} h(n)^{1/n} = 1, the ratio h(x)/h(2x) is integrable on (0,∞).

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Background

Handelman introduced a maximal function H_h(a) = sup_{b≥a} h(b)/h(a+b) and observed that for log-convex h this simplifies to H_h(x) = h(x)/h(2x). Motivated by this, he posed a question relating integrability of h to integrability of h(x)/h(2x).

This paper revisits that question directly in the introduction, presenting it as Question 1 before constructing a counterexample in Section 2.1.

References

Question 1. If h : (0,∞) → (0,∞) is a log convex function that is integrable on (0,∞) and satisfies limn→∞ h(n) 1/n= 1, then is it true that h(x) /h(2x) is also integrable on (0,∞)?

On Some Convexity Questions of Handelman (2402.10970 - Simanek, 14 Feb 2024) in Section 1 (Introduction), Question 1