REVIEW
Unit fraction representations using shifted Golomb primes
Number Theory · Submitted 4 Nov 2026 · 33 references
Pith's verdict: A real theorem for a genuinely sparse sequence — the supporting AP and non-smooth estimates are the durable part — but Proposition 6.1's stated hypotheses contradict each other and don't cover the way Section 6 uses it.
T0 · AI review
Why Pith says this
Highlight any text to comment on it.
Referee report
The paper
The paper claims
The paper proves that for every fixed nonzero integer $h$, the numbers $g-h$ with $g$ a Golomb prime form a reciprocal basis for the positive rationals: every $a/b$, subject only to the congruence conditions the problem forces, is a…
The reading
What carries the argument
The engine is a Croot-type proposition (Proposition 6.1): for a set $A$ of shifted primes inside an interval $(M,N]$ whose elements are $N^{0.99}$-power-smooth, carry about $\log\log N$ prime factors, spread their reciprocal mass evenly over prime powers, and have $R(A)$ not too small, one can hit every target of the shape $x/Q$ (with $Q=\mathrm{lcm}(A)$) by a sub-sum of reciprocals. The obstruction is that inside a single narrow interval the shifted Golomb primes have reciprocal sum only of order $1/\log\log N$, far too little to reach a fixed fraction. The author's fix is to slice the range into $J\asymp 333\log\log N$ blocks $(N_{j+1},N_j]$ with $N_{j+1}=N_j e^{-0.003}$, each contributing $\Theta(1/\log\log N)$, prune each block to satisfy the proposition using Theorem 1.4 and Theorem 1.5, and then arrange one integer $P$, divisible by $b$ and of size about $(\log\log N)^2$, that divides the lcm of every pruned block. That shared modulus lets the fractions $y_j/P$ be represented block by block and summed to $a/b$ with all denominators distinct.
Extended reading notes
Core claim
The central claim is Theorem 1.3: let $h\neq 0$ and let $a,b\in\mathbb{Z}^+$ with $(a,b)=1$, $(b,h)=1$ and $(b,h-1)$ Golomb-prime-free; then for every $y\ge |h|$ there is a finite set $B$ of Golomb primes, all exceeding $y$, with $a/b=\sum_{g\in B} 1/(g-h)$. The two conditions on $b$ are shown in Section 6 to be necessary, not technical: if a prime $p$ divided both $b$ and $h$ then $p$ would have to equal some $g>|h|\ge p$, and if a Golomb prime $q$ divided both $b$ and $h-1$ then $q\mid g-1$, which the defining sieve forbids. The proof rests on two new distribution results: a Siegel--Walfisz-type asymptotic for $|\{g\le x : g\equiv h \pmod b\}|$ that holds for $b\le(\log x)^A$ with the expected Euler-product correction for Golomb primes dividing $b$, and an upper bound saying that among Golomb primes $g\le x$ in the class $h \bmod b$, at most a proportion $0.259+o(1)$ have $g-h$ divisible by a prime power exceeding $x^{0.99}$.
Load-bearing premise
The deduction applies Proposition 6.1 to blocks whose endpoints satisfy $M=N_{j+1}=N_j e^{-0.003}$, whereas the proposition as printed requires $M\le N/10^4$; the appendix appears to use only $M\ge N^{0.997}$, so the main theorem is formally resting on the proposition holding in that wider range rather than the stated one.
Editorial extensions
If this is right
- The reciprocal sum over shifted Golomb primes inherits a basis property: for every nonzero $h$ and every target fraction, one can reach or exceed it using distinct terms $1/(g-h)$, so the associated series diverges and is unbounded on distinct terms.
- Golomb primes are equidistributed among the allowed residue classes $h \bmod b$ for $b\le(\log x)^A$, with the same $1/\varphi(b)$ factor as the primes and an explicit correction $\prod_{q\mid b, q\in G}(1-1/(q-1))^{-1}$ for Golomb primes dividing the modulus.
- At least a positive proportion, roughly $0.741$ of the expected count, of shifted Golomb primes in a progression remain after discarding those with a prime-power divisor above $x^{0.99}$, which is what makes the Croot-type proposition applicable at all.
- A remark in the paper observes that a recently announced zero-free half-plane $\mathrm{Re}\,s>7/8$ for Dirichlet $L$-functions would push the equidistribution theorem from $b\le(\log x)^A$ to $b\le x^{1/8-2\varepsilon}$ with the same method.
Reading between the lines
- The Golomb primes are one instance of a family: primes sieved by forbidding one residue class modulo each earlier member. The same three ingredients used here (equidistribution in progressions, a bound on non-smooth shifts, and a shared modulus across blocks) should give reciprocal-basis theorems for other sieves of this shape, so the argument reads as a template rather than a one-off.
- The author states the method does not extend to an arbitrary positive-density subset of the Golomb primes, which leaves an obvious gradient to test: whether a random subset of the Golomb primes of relative density $(\log\log x)^{-\theta}$ still represents every rational, and where the threshold sits.
- The common-modulus step is the part most likely to generalise beyond this paper's setting: any sparse set whose elements' least common multiples can be forced to carry a fixed modulus of size $\mathrm{polylog}\log$ can be assembled block by block, which suggests a reusable criterion independent of the specific arithmetic of Golomb primes.
- A concrete check a reader can run: take the smallest cases, such as $h=1$, $a/b=1/2$, and search for short explicit subsets of $\{g-1\}$ summing to it, to see the block structure and modulus in action at small scale.
Original abstract
We prove that every positive rational number is a sum of distinct unit fractions with denominators of the form $g-h$, where $g$ is a Golomb prime and $h$ is a fixed nonzero integer, as long as the necessary congruence conditions are satisfied. Golomb primes, introduced by Golomb in 1955, are a natural analogue of the primes. Erd\H{o}s showed that the relative density of Golomb primes among the primes up to $N$ is about $1/\log\log N$, so they form a sparse subset of the primes. Our result is an analogue of Bloom's result on unit fraction representations using shifted primes, for this sparse subset of the primes. A key ingredient in our proof is a Siegel--Walfisz-type theorem for Golomb primes in arithmetic progressions, which we also prove here.
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
We prove that every positive rational number is a sum of distinct unit fractions with denominators of the form $g-h$, where $g$ is a Golomb prime and $h$ is a fixed nonzero integer, as long as the necessary congruence conditions are satisfied. Golomb primes, introduced by Golomb in 1955, are a natural analogue of the primes. Erd\H{o}s showed that the relative density of Golomb primes among the primes up to $N$ is about $1/\log\log N$, so they form a sparse subset of the primes. Our result is an analogue of Bloom's result on unit fraction representations using shifted primes, for this sparse subset of the primes. A key ingredient in our proof is a Siegel--Walfisz-type theorem for Golomb primes in arithmetic progressions, which we also prove here.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We prove that every positive rational number is a sum of distinct unit fractions with denominators of the form $g-h$, where $g$ is a Golomb prime and $h$ is a fixed nonzero integer, as long as the necessary congruence conditions are satisfied. | result 0.86 | 0.96 | 0.96 | asserted 1.00 |
| s1 | Golomb primes, introduced by Golomb in 1955, are a natural analogue of the primes. | background 1.00 | 0.04 | 0.01 | asserted 1.00 |
| s2 | Erd\H{o}s showed that the relative density of Golomb primes among the primes up to $N$ is about $1/\log\log N$, so they form a sparse subset of the primes. | background 1.00 | 0.03 | 0.02 | asserted 0.99 |
| s3 | Our result is an analogue of Bloom's result on unit fraction representations using shifted primes, for this sparse subset of the primes. | interpretation 0.85 | 0.63 | 0.08 | asserted 1.00 |
| s4 | A key ingredient in our proof is a Siegel--Walfisz-type theorem for Golomb primes in arithmetic progressions, which we also prove here. | method 0.68 | 0.96 | 0.03 | asserted 1.00 |
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
- C citations
- R cross-paper relations
References
Discussion
Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.