Erdős’s ratio-growth problem and a quantitative Haight-type theorem

Boon Suan Ho

For nondecreasing F tending to infinity, an infinite-measure measurable set S of positive reals with no distinct-point integer quotient and |S∩(0,x)|≥F(x) eventually exists exactly when ∫₁∞ F(x)/x² dx is finite.

Sources for this record

What was already known

Haight and Szemerédi established existence of such a set, and Erdős asked how fast its mass could grow.

AI involvement AI-centered

Ho credits GPT-5.4 Pro with materially generating and shaping the argument through dialogue. Ho directed, revised and explained the work; Tao’s later proof is separately credited.

The author explicitly describes material model generation of the core arguments within human-guided iterative work.

Importance Notable

Gives the sharp obstruction to growth for the integer-ratio question.

Limitations

Ho reports vetting the main construction, and Tao later explained a shorter proof using Bohr sets and simultaneous approximation. A complete human check of Ho’s exact manuscript is not documented; Tao also flagged missing attribution.

Technical verification Partial

Ho says he vetted the main ideas, which checks the central construction's outline but does not document a complete rigorous proof check. Sothanaphan's reported standard AI check and Tao's replacement exposition do not by themselves establish a complete check of Ho's original argument.

Human understanding Full

Ho explains the logarithmic-comb and block-deletion mechanism in detail; Tao independently explains the central idea using simultaneous approximation and Bohr sets.

Correction and publication history