GPT 6 Astra Ultra attempt on Math-5547
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Erdős Problem #279: independent continuation
Date: 2026-09-23. Research attempt; no claim of a new published result.1) TARGET AND SOURCE AUDIT
For each $k\ge3$, choose $0\le a_p<p$ for all primes so every sufficiently large integer equals $a_p+tp$ for some prime $p$ and $t\ge k$.All supplied versions considered: 279.tex. The supplied density-zero exception theorem is valid but cannot establish finiteness. I test the natural coherent choices of residues and prove they all have infinite exceptions.
2) WORK
Fix an integer $r\ge0$ and choose $a_p$ to be its least nonnegative residue modulo $p$. For any prime $q>r$, let $m=r+q$. If $m=a_p+tp$, then congruence modulo $p$ implies $p\mid(m-r)=q$, so $p=q$. Since $q>r$, $a_q=r$, and therefore $t=1$. Thus every $m=r+q$ with $q>r$ prime is exceptional whenever $k\ge2$. Infinitely many such $q$ exist. No single fixed integer residue pattern can solve the problem.For $r=0$ this describes the obstruction especially precisely. If $m$ is composite and $m\ge k^2$, its smallest prime divisor $p$ satisfies $p\le\sqrt m$, so $m/p\ge\sqrt m\ge k$, yielding a representation. Every prime remains exceptional. Hence for the zero residues the exceptional set is exactly the primes, up to finitely many smaller integers.
This exhibits a concrete family compatible with the source's density-zero conclusion while still having infinitely many exceptions; no probabilistic or heuristic density estimate is needed for the noncoverage proof.
3) ADVERSARIAL VERIFICATION
The quotient restriction is essential: without $t\ge k$, a prime covers itself using $p=m,t=1$. The fixed shift is chosen once, independently of $p$. The argument does not treat arbitrary independently chosen residues and therefore is not a disproof of the question.4) FINAL
UNRESOLVED. A successful residue choice must avoid these coherent-shift obstructions while ensuring coverage for every sufficiently large integer. No such choice has been constructed.5) SOURCES CHECKED
Full279.tex read; exact $k\ge3$ quantifier checked in the formal-conjectures ErdosProblems/279.lean file on 2026-09-23.