REVIEW
The exceptional set of Goldbach numbers among polynomial values
Number Theory · Submitted 6 Nov 2026 · 10 references
Pith's verdict: Clean, genuinely new exponents, but Theorem 1 is announced unconditionally while riding on theta<=7/8 from an unverified OpenAI preprint — a worthy referee job, provided the hypothesis is brought onto the theorem statement.
T0 · AI review
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Referee report
The paper
The paper claims
All but $N^{\alpha_k+o(1)}$ of the numbers $2\phi(n)$, $n\le N$, are sums of two primes, with $\alpha_2=1/2$, $\alpha_3=5/8$, $\alpha_4=3/4$, $\alpha_k=1-1/(k+1)$ for $k>4$, conditional on a fixed zero-free half-plane for Dirichlet…
The reading
What carries the argument
The engine is a Hölder step that writes the weighted prime sum as $|S_w(\alpha)|^2=(|S_w(\alpha)|^4)^{1/q}(|S_w(\alpha)|^2)^{1-2/q}$ and multiplies it by $K(\alpha)=\sum_{n\in A}e(-2\phi(n)\alpha)$, the exponential sum over the exceptional index set $A\subseteq\{1,\dots,N\}$ of size $Z$ whose values fail Goldbach. On the major arcs, with the smooth weight $w$ equal to 1 on $[1/8,7/8]$, a quoted asymptotic gives the representation count $R_1(m)=S(m)I_w(m)+O(X^{1-c})$, where the singular series satisfies $S(m)\ge 2C_0>0$ and $I_w(m)\gg X$, so every $m=2\phi(n)$ has many weighted prime-pair representations unless $n\in A$; summing $R(2\phi(n))=0$ then forces the minor-arc integral of $S_w^2K$ to be large. Hölder's inequality bounds that integral by the minor-arc fourth moment of $S_w$ (quoted, needing $\theta<11/12$), the Parseval identity $\int|S_w|^2\ll XL$, and a $q$-th moment estimate for $K$ that is uniform in the subset $A$ and essentially sharp in its size, $\int|K|^q\ll N^{b+\varepsilon}Z^{q/2}$. The three suppliers of that estimate are Lemma G ($q=4$, $b=0$, via the factorization $(x-y)(a(x+y)+b)=t$), Theorem F ($q=8$, $b=1$, for degree at least 3), and Corollary E ($q=k(k+1)$, $b=k(k-1)/2$, from the weighted Vinogradov mean-value theorem). The outcome is the master bound $Z\ll N^{(k+2b)/q+\varepsilon}$, and the degree-wise minima of $(k+2b)/q$ are exactly $\alpha_2=1/2$, $\alpha_3=5/8$, $\alpha_4=3/4$, $\alpha_k=1-1/(k+1)$.
Extended reading notes
Core claim
The central claim, Theorem 1, is: for every fixed $\phi\in\mathbb{Z}[x]$ of degree $k\ge 2$ with positive leading coefficient, and every $\varepsilon>0$, the count $E_{k,\phi}(N)$ of indices $n\le N$ for which $2\phi(n)$ is not a sum of two primes satisfies $E_{k,\phi}(N)\ll_{\phi,\varepsilon} N^{\alpha_k+\varepsilon}$, with $\alpha_2=1/2$, $\alpha_3=5/8$, $\alpha_4=3/4$, and $\alpha_k=1-1/(k+1)$ for $k>4$. The paper is explicit that the proof is conditional: it needs $\theta<11/12$, where $\theta$ is the supremum of the real parts of nontrivial zeros of all primitive Dirichlet $L$-functions, and it imports this hypothesis from an external source in the stronger form $\theta\le 7/8$ (its Theorem A, quoted in Section 2). Given that input, two quoted theorems do the analytic work: a minor-arc fourth-moment bound for the weighted prime sum, $\int_{\mathfrak m}|S_w(\alpha)|^4\,d\alpha\ll X^{5/2}(\log X)^{100}$, and a major-arc asymptotic relating the representation integral to the singular series $S(m)$ times a weight convolution of size $\gg X$. The new contribution is the polynomial side: matching the prime fourth moment against mean-value estimates for exponential sums over arbitrary subsets of polynomial sequences, the proof shows the exceptional set for $2\phi(n)$ has size at most $N^{(k+2b)/q+\varepsilon}$, and the three families of subset moment estimates — an elementary divisor argument for degree 2, an eighth-moment discrete-restriction bound for degrees 3 and 4, and Vinogradov mean-value estimates for $k>4$ — convert that master bound into the exponents of Theorem 1.
Load-bearing premise
The load-bearing premise is Theorem A — the assertion, quoted from an external preprint and neither proved nor summarized in this paper, that all primitive Dirichlet $L$-functions are zero-free in the fixed half-plane $\operatorname{Re}s>7/8$; the paper's own summary is that the proof needs only $\theta<11/12$ and Theorem A supplies it, so if that quoted premise fails, the minor-arc fourth-moment bound and the major-arc asymptotic — and with them the whole theorem — have no support.
Editorial extensions
If this is right
- For every fixed integer polynomial $\phi$ of degree $k\ge 2$, the even numbers $2\phi(n)$ are sums of two primes for all but $N^{\alpha_k+o(1)}$ of the indices $n\le N$, a set of density zero; for quadratic $\phi$ the saving is strongest, at most $N^{1/2+o(1)}$ exceptions.
- The exponents are the first explicit power savings for Goldbach numbers among polynomial values at every degree, improving on the earlier $N(\log N)^{-A}$ and $N^{1-c_0/k}$ bounds, whose previous saving in the exponent was not made explicit.
- For the thin sequences $2\lfloor a(n+\beta)^r\rfloor^k$, for almost every $\beta\in[0,1]$ and any $r>1/(1-\alpha_k)$ — for example $r>2$ when $k=2$ — every sufficiently large term is a sum of two primes, and the sequence's counting function is asymptotic to $(X/2a^k)^{1/(kr)}$.
- Because $\alpha_k=1-1/(k+1)$ for $k>4$ approaches 1 as the degree grows, the saving over the trivial bound $N$ shrinks with $k$; the best constants occur at low degree, where the eighth-moment estimate beats the general mean-value formula.
Reading between the lines
- If the quoted zero-free half-plane is ever proved and the minor-arc fourth-moment exponent pushed below $5/2$, the displayed chain (4.6)–(4.7) transfers that improvement linearly: replacing the $X^{5/2}$ factor by $X^{5/2-\delta}$ lowers every $\alpha_k$ by $2k\delta/q$, so the paper's exponents are best read as a scaffold attached to the prime fourth moment rather than as a hard floor.
- The explicit-$\beta$ question the authors leave open admits a direct computational probe: for $\beta=0$, $k=2$, $r=3$, one can test whether every large $n$ gives $2n^6$ as a sum of two primes; a single counterexample would answer the open question in the negative, while agreement over a long range would only sharpen it.
- For $k\ge 5$ the binding constraint is the sparse-subset mean value, not the prime machinery: any uniform mean-value theorem of the shape $N^{b+\varepsilon}Z^{q/2}$ would feed the same master bound, so progress on discrete restriction for sparse polynomial sequences would lower $\alpha_k$ without altering the circle-method side of the proof.
Original abstract
Let $\phi$ be a fixed polynomial with integer coefficients, positive leading coefficient and degree $k\geq2$. We prove that the values $2\phi(n)$, $1\leq n\leq N$, can be written as the sum of two primes, apart from at most $N^{\alpha_k+o(1)}$ exceptional indices, where $\alpha_k<1$. For quadratic polynomials the exponent is $1/2$, for cubic polynomials $5/8$, for quartic polynomials $3/4$, and for $k>4$ it is $1-1/(k+1)$. The proof combines a fourth-moment estimate over primes with mean-value estimates over arbitrary subsets of polynomial sequences.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
Let $\phi$ be a fixed polynomial with integer coefficients, positive leading coefficient and degree $k\geq2$. We prove that the values $2\phi(n)$, $1\leq n\leq N$, can be written as the sum of two primes, apart from at most $N^{\alpha_k+o(1)}$ exceptional indices, where $\alpha_k<1$. For quadratic polynomials the exponent is $1/2$, for cubic polynomials $5/8$, for quartic polynomials $3/4$, and for $k>4$ it is $1-1/(k+1)$. The proof combines a fourth-moment estimate over primes with mean-value estimates over arbitrary subsets of polynomial sequences.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Let $\phi$ be a fixed polynomial with integer coefficients, positive leading coefficient and degree $k\geq2$. | background 0.97 | 0.09 | 0.02 | asserted 0.53 |
| s1 | We prove that the values $2\phi(n)$, $1\leq n\leq N$, can be written as the sum of two primes, apart from at most $N^{\alpha_k+o(1)}$ exceptional indices, where $\alpha_k<1$. | result 0.97 | 0.96 | 0.95 | asserted 1.00 |
| s2 | For quadratic polynomials the exponent is $1/2$, for cubic polynomials $5/8$, for quartic polynomials $3/4$, and for $k>4$ it is $1-1/(k+1)$. | result 1.00 | 0.88 | 0.14 | asserted 1.00 |
| s3 | The proof combines a fourth-moment estimate over primes with mean-value estimates over arbitrary subsets of polynomial sequences. | method 1.00 | 0.88 | 0.02 | asserted 0.98 |
What was examined, and what was not
- arXiv listing abstract v1
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
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References
Discussion
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