GPT 6 Astra Ultra attempt on Math-689
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Erdős Problem #143: independent continuation
Date: 2026-09-23. Research attempt; no claim of a new published result.1) TARGET AND SOURCE AUDIT
If $\mathcal A\subset(1,\infty)$ satisfies $|kx-y|\ge1$ for distinct $x,y\in\mathcal A$ and every positive integer $k$, must $\sum_{x\in\mathcal A}1/(x\log x)$ converge?All supplied versions considered: 143.tex. The source reduces convergence to weighted block masses and treats rational sets with finitely many denominators. There are repairable errors: its logarithmic comparison needs $a\ge q^2$, not $a\ge2q$; its Abel lemma needs local finiteness rather than mere countability. The hypothesis supplies local finiteness, since distinct points have distance at least one.
2) WORK
A simpler corrected bounded-denominator proof.
Suppose every denominator divides an integer $Q$. The set $B=\{Qx:x\in\mathcal A\}\subset\mathbb N$ is primitive: if $b'=kb$ for distinct members, then $y=kx$, violating the hypothesis. By the classical primitive-set convergence theorem, \[ \sum_{b\in B}{1\over b\log b}<\infty. \] For $b\ge Q^2$ (and $b>1$), $\log(b/Q)\ge\tfrac12\log b$, so \[ {1\over (b/Q)\log(b/Q)}\le {2Q\over b\log b}. \] The finitely many smaller $b$ contribute a finite amount. Thus the desired series converges in this subclass. Taking the least common multiple of the finitely many reduced denominators obtains the source's conclusion using one primitive set rather than separate slices.Exact summation statement.
Define $U(t)=\sum_{2<x\le t,\ x\in\mathcal A}1/x$. Local finiteness makes this finite, and integration by parts gives exactly \[ \sum_{2<x\le X}{1\over x\log x}={U(X)\over\log X}+\int_2^X{U(t)\over t(\log t)^2}\,dt. \] There is no uncontrolled boundary term, since $U(2)=0$. The one-separation assumption allows at most two points in $(1,2]$, so restoring these terms is legitimate. This repairs the stated generality without extending convergence to arbitrary real sets.3) ADVERSARIAL VERIFICATION
The comparison fails at $a=2q$ when $q$ is large: $\log(a/q)=\log2$ whereas $\tfrac12\log a$ grows. Replacing the cutoff by $q^2$ fixes the proof. A countable set can accumulate near one, so countability alone cannot justify discarding finitely many small elements. Bounded denominators are still a restrictive hypothesis.4) FINAL
UNRESOLVED. No control of the integral is established for a general dilation-separated real set. The repaired subclass theorem does not bridge that remaining gap.5) SOURCES CHECKED
Read all of143.tex; checked Lichtman, A proof of the Erdős primitive set conjecture, https://arxiv.org/abs/2202.02384, on 2026-09-23 for the primitive-set input. The argument imports that known convergence theorem and does not label it novel.