Bounded gaps between primes
This is the home page for the Polymath8 project "bounded gaps between primes".
Contents
World records
 [math]H[/math] is a quantity such that there are infinitely many pairs of consecutive primes of distance at most [math]H[/math] apart. Would like to be as small as possible (this is a primary goal of the Polymath8 project).
 [math]k_0[/math] is a quantity such that every admissible [math]k_0[/math]tuple has infinitely many translates which each contain at least two primes. Would like to be as small as possible. Improvements in [math]k_0[/math] lead to improvements in [math]H[/math]. (The relationship is roughly of the form [math]H \sim k_0 \log k_0[/math]; see the page on finding narrow admissible tuples.)
 [math]\varpi[/math] is a technical parameter related to a specialized form of the ElliottHalberstam conjecture. Would like to be as large as possible. Improvements in [math]\varpi[/math] lead to improvements in [math]k_0[/math], as described in the page on DicksonHardyLittlewood theorems. In more recent work, the single parameter [math]\varpi[/math] is replaced by a pair [math](\varpi,\delta)[/math] (in previous work we had [math]\delta=\varpi[/math]). These estimates are obtained in turn from Type I, Type II, and Type III estimates, as described at the page on distribution of primes in smooth moduli.
In this table, infinitesimal losses in [math]\delta,\varpi[/math] are ignored.
Date  [math]\varpi[/math] or [math](\varpi,\delta)[/math]  [math]k_0[/math]  [math]H[/math]  Comments 

14 May  1/1,168 (Zhang)  3,500,000 (Zhang)  70,000,000 (Zhang)  All subsequent work is based on Zhang's breakthrough paper. 
21 May  63,374,611 (Lewko)  Optimises Zhang's condition [math]\pi(H)\pi(k_0) \gt k_0[/math]; can be reduced by 1 by parity considerations  
28 May  59,874,594 (Trudgian)  Uses [math](p_{m+1},\ldots,p_{m+k_0})[/math] with [math]p_{m+1} \gt k_0[/math]  
30 May  59,470,640 (Morrison)
58,885,998? (Tao) 59,093,364 (Morrison) 57,554,086 (Morrison) 
Uses [math](p_{m+1},\ldots,p_{m+k_0})[/math] and then [math](\pm 1, \pm p_{m+1}, \ldots, \pm p_{m+k_0/21})[/math] following [HR1973], [HR1973b], [R1974] and optimises in m  
31 May  2,947,442 (Morrison)
2,618,607 (Morrison) 
48,112,378 (Morrison)
42,543,038 (Morrison) 42,342,946 (Morrison) 
Optimizes Zhang's condition [math]\omega\gt0[/math], and then uses an improved bound on [math]\delta_2[/math]  
1 Jun  42,342,924 (Tao)  Tiny improvement using the parity of [math]k_0[/math]  
2 Jun  866,605 (Morrison)  13,008,612 (Morrison)  Uses a further improvement on the quantity [math]\Sigma_2[/math] in Zhang's analysis (replacing the previous bounds on [math]\delta_2[/math])  
3 Jun  1/1,040? (v08ltu)  341,640 (Morrison)  4,982,086 (Morrison)
4,802,222 (Morrison) 
Uses a different method to establish [math]DHL[k_0,2][/math] that removes most of the inefficiency from Zhang's method. 
4 Jun  1/224?? (v08ltu)
1/240?? (v08ltu) 
4,801,744 (Sutherland)
4,788,240 (Sutherland) 
Uses asymmetric version of the HensleyRichards tuples  
5 Jun  34,429? (Paldi/v08ltu)  4,725,021 (Elsholtz)
4,717,560 (Sutherland) 397,110? (Sutherland) 4,656,298 (Sutherland) 389,922 (Sutherland) 388,310 (Sutherland) 388,284 (Castryck) 388,248 (Sutherland) 387,982 (Castryck) 387,974 (Castryck) 
[math]k_0[/math] bound uses the optimal Bessel function cutoff. Originally only provisional due to neglect of the kappa error, but then it was confirmed that the kappa error was within the allowed tolerance.
[math]H[/math] bound obtained by a hybrid Schinzel/greedy (or "greedygreedy") sieve  
6 Jun  

387,960 (Angelveit)
387,904 (Angeltveit)

Improved [math]H[/math]bounds based on experimentation with different residue classes and different intervals, and randomized tiebreaking in the greedy sieve. 
7 Jun 

26,024? (vo8ltu) 
387,534 (pedantSutherland) 
Many of the results ended up being retracted due to a number of issues found in the most recent preprint of Pintz. 
Jun 8  286,224 (Sutherland)
285,752 (pedantSutherland) 
values of [math]\varpi,\delta,k_0[/math] now confirmed; most tuples available on dropbox. New bounds on [math]H[/math] obtained via iterated merging using a randomized greedy sieve.  
Jun 9  181,000*? (Pintz)  2,530,338*? (Pintz)  New bounds on [math]H[/math] obtained by interleaving iterated merging with local optimizations.  
Jun 10  23,283? (Harcos/v08ltu)  285,210 (Sutherland)  More efficient control of the [math]\kappa[/math] error using the fact that numbers with no small prime factor are usually coprime  
Jun 11  252,804 (Sutherland)  More refined local "adjustment" optimizations, as detailed here.
An issue with the [math]k_0[/math] computation has been discovered, but is in the process of being repaired.  
Jun 12  22,951 (Tao/v08ltu)
22,949 (Harcos) 
249,180 (Castryck)  Improved bound on [math]k_0[/math] avoids the technical issue in previous computations.  
Jun 13  
Jun 14  248,898 (Sutherland)  
Jun 15  [math]348\varpi+68\delta \lt 1[/math]? (Tao)  6,330? (v08ltu)
6,329? (Harcos) 6,329 (v08ltu) 
60,830? (Sutherland)  Taking more advantage of the [math]\alpha[/math] convolution in the Type III sums 
Jun 16  [math]348\varpi+68\delta \lt 1[/math] (v08ltu)


60,760* (Sutherland)

Attempting to make the Weyl differencing more efficient; unfortunately, it did not work 
Jun 18  5,937? (Pintz/Tao/v08ltu)
5,672? (v08ltu) 5,459? (v08ltu) 5,454? (v08ltu) 5,453? (v08ltu) 
60,740 (xfxie)
58,866? (Sun) 53,898? (Sun) 53,842? (Sun) 
A new truncated sieve of Pintz virtually eliminates the influence of [math]\delta[/math]  
Jun 19  5,455? (v08ltu)
5,453? (v08ltu) 5,452? (v08ltu) 
53,774? (Sun)
53,672*? (Sun) 
Some typos in [math]\kappa_3[/math] estimation had placed the 5,454 and 5,453 values of [math]k_0[/math] into doubt; however other refinements have counteracted this  
Jun 20  [math]178\varpi + 52\delta \lt 1[/math]? (Tao)
[math]148\varpi + 33\delta \lt 1[/math]? (Tao) 
Replaced "completion of sums + Weil bounds" in estimation of incomplete Kloostermantype sums by "Fourier transform + Weyl differencing + Weil bounds", taking advantage of factorability of moduli  
Jun 21  [math]148\varpi + 33\delta \lt 1[/math] (v08ltu)  1,470 (v08ltu)
1,467 (v08ltu) 
12,042 (Engelsma)  Systematic tables of tuples of small length have been set up here and here (update: As of June 27 these tables have been merged and uploaded to an online database of current bounds on [math]H(k)[/math] for [math]k[/math] up to 5000). 
Jun 22  

Slight improvement in the [math]\tilde \theta[/math] parameter in the Pintz sieve; unfortunately, it does not seem to currently give an actual improvement to the optimal value of [math]k_0[/math]  
Jun 23  1,466 (Paldi/Harcos)  12,006 (Engelsma)  An improved monotonicity formula for [math]G_{k_01,\tilde \theta}[/math] reduces [math]\kappa_3[/math] somewhat  
Jun 24  [math](134 + \tfrac{2}{3}) \varpi + 28\delta \le 1[/math]? (v08ltu)
[math]140\varpi + 32 \delta \lt 1[/math]? (Tao)

1,268? (v08ltu)  10,206? (Engelsma)  A theoretical gain from rebalancing the exponents in the Type I exponential sum estimates 
Jun 25  [math]116\varpi+30\delta\lt1[/math]? (FouvryKowalskiMichelNelson/Tao)  1,346? (Hannes)
1,007? (Hannes) 
10,876? (Engelsma)  Optimistic projections arise from combining the GrahamRingrose numerology with the announced FouvryKowalskiMichelNelson results on d_3 distribution 
Jun 26  [math]116\varpi + 25.5 \delta \lt 1[/math]? (Nielsen)
[math](112 + \tfrac{4}{7}) \varpi + (27 + \tfrac{6}{7}) \delta \lt 1[/math]? (Tao) 
962? (Hannes)  7,470? (Engelsma)  Beginning to flesh out various "levels" of Type I, Type II, and Type III estimates, see this page, in particular optimising van der Corput in the Type I sums. Integrated tuples page now online. 
Jun 27  [math]108\varpi + 30 \delta \lt 1[/math]? (Tao)  902? (Hannes)  6,966? (Engelsma)  Improved the Type III estimates by averaging in [math]\alpha[/math]; also some slight improvements to the Type II sums. Tuples page is now accepting submissions. 
Jul 1  [math](93 + \frac{1}{3}) \varpi + (26 + \frac{2}{3}) \delta \lt 1[/math]? (Tao) 
873? (Hannes)

Refactored the final CauchySchwarz in the Type I sums to rebalance the offdiagonal and diagonal contributions  
Jul 5  [math] (93 + \frac{1}{3}) \varpi + (26 + \frac{2}{3}) \delta \lt 1[/math] (Tao) 
Weakened the assumption of [math]x^\delta[/math]smoothness of the original moduli to that of double [math]x^\delta[/math]dense divisibility  
Jul 10  7/600? (Tao)  An in principle refinement of the van der Corput estimate based on exploiting additional averaging  
Jul 19  [math](85 + \frac{5}{7})\varpi + (25 + \frac{5}{7}) \delta \lt 1[/math]? (Tao)  A more detailed computation of the Jul 10 refinement  
Jul 20  Jul 5 computations now confirmed  
Jul 27  633? (Tao)
632? (Harcos) 
4,686? (Engelsma)  
Jul 30  [math]168\varpi + 48\delta \lt 1[/math]**? (Tao)  1,788**? (Tao)  14,994**? (Sutherland)  Bound obtained without using Deligne's theorems. 
Aug 17  1,783**? (xfxie)  14,950**? (Sutherland)  
Oct 3  13/1080?? (Nelson/Michel/Tao)  604?? (Tao)  4,428?? (Engelsma)  Found an additional variable to apply van der Corput to 
Oct 11  [math]\frac{1080}{13}\varpi + \frac{330}{13} \delta \lt 1[/math]? (Tao)  603? (xfxie)  4,422?(Engelsma)  Worked out the dependence on [math]\delta[/math] in the Oct 3 calculation 
Legend:
 ?  unconfirmed or conditional
 ??  theoretical limit of an analysis, rather than a claimed record
 *  is majorized by an earlier but independent result
 **  bound does not rely on Deligne's theorems
 strikethrough  values relied on a computation that has now been retracted
See also the article on Finding narrow admissible tuples for benchmark values of [math]H[/math] for various key values of [math]k_0[/math].
Polymath threads
 I just can’t resist: there are infinitely many pairs of primes at most 59470640 apart, Scott Morrison, 30 May 2013. Inactive
 The prime tuples conjecture, sieve theory, and the work of GoldstonPintzYildirim, MotohashiPintz, and Zhang, Terence Tao, 3 June 2013. Inactive
 Polymath proposal: bounded gaps between primes, Terence Tao, 4 June 2013. Inactive
 Online reading seminar for Zhang’s “bounded gaps between primes”, Terence Tao, 4 June 2013. Inactive
 More narrow admissible sets, Scott Morrison, 5 June 2013. Inactive
 The elementary Selberg sieve and bounded prime gaps, Terence Tao, 8 June 2013. Inactive
 A combinatorial subset sum problem associated with bounded prime gaps, Terence Tao, 10 June 2013. Inactive
 Further analysis of the truncated GPY sieve, Terence Tao, 11 June 2013. Inactive
 Estimation of the Type I and Type II sums, Terence Tao, 12 June 2013. Inactive
 Estimation of the Type III sums, Terence Tao, 14 June 2013. Inactive
 A truncated elementary Selberg sieve of Pintz, Terence Tao, 18 June, 2013. Inactive
 Bounding short exponential sums on smooth moduli via Weyl differencing, Terence Tao, 22 June, 2013. Inactive
 The distribution of primes in densely divisible moduli, Terence Tao, 23 June, 2013. Inactive
 Bounded gaps between primes (Polymath8) – a progress report, Terence Tao, 30 June 2013. Inactive
 The quest for narrow admissible tuples, Andrew Sutherland, 2 July 2013. Inactive
 The distribution of primes in doubly densely divisible moduli, Terence Tao, 7 July 2013. Inactive.
 An improved Type I estimate, Terence Tao, 27 July 2013. Inactive
 Polymath8: writing the paper, Terence Tao, 17 August 2013. Inactive
 Polymath8: writing the paper, II, Terence Tao, 2 September 2013. Inactive
 Polymath8: writing the paper, III, Terence Tao, 22 September 2013. Active
Writeup
Files for the draft paper for this project may be found in this directory. The compiled PDF is available here.
Here are the Polymath8 grant acknowledgments.
Code and data
 HenselyRichards sequences, Scott Morrison
 A mathematica notebook for finding k_0, Scott Morrison
 python implementation, Avi Levy
 ktuple pattern data, Thomas J Engelsma
 Sifted sequences, Vit Tucek
 Other sifted sequences, Christian Elsholtz
 Size of largest admissible tuples in intervals of length up to 1050, Clark and Jarvis
 C implementation of the "greedygreedy" algorithm, Andrew Sutherland
 Dropbox for sequences, pedant
 Spreadsheet for admissible sequences, Vit Tucek
 Java code for optimising a given tuple V1.1, xfxie
Tuples applet
Here is a small javascript applet that illustrates the process of sieving for an admissible 632tuple of diameter 4680 (the sieved residue classes match the example in the paper when translated to [0,4680]).
The same applet can also be used to interactively create new admissible tuples. The default sieve interval is [0,400], but you can change the diameter to any value you like by adding “?d=nnnn” to the URL (e.g. use https://math.mit.edu/~primegaps/sieve.html?d=4680 for diameter 4680). The applet will highlight a suggested residue class to sieve in green (corresponding to a greedy choice that doesn’t hit the end points), but you can sieve any classes you like.
You can also create sieving demos similar to the k=632 example above by specifying a list of residues to sieve. A longer but equivalent version of the “?ktuple=632″ URL is
The numbers listed after “r=” are residue classes modulo increasing primes 2,3,5,7,…, omitting any classes that do not require sieving — the applet will automatically skip such primes (e.g. it skips 151 in the k=632 example).
A few caveats: You will want to run this on a PC with a reasonably wide display (say 1360 or greater), and it has only been tested on the current versions of Chrome and Firefox.
Errata
Page numbers refer to the file linked to for the relevant paper.
 Errata for Zhang's "Bounded gaps between primes"
 Page 5: In the first display, [math]\mathcal{E}[/math] should be multiplied by [math]\mathcal{L}^{2k_0+2l_0}[/math], because [math]\lambda(n)^2[/math] in (2.2) can be that large, cf. (2.4).
 Page 14: In the final display, the constraint [math](n,d_1=1[/math] should be [math](n,d_1)=1[/math].
 Page 35: In the display after (10.5), the subscript on [math]{\mathcal J}_i[/math] should be deleted.
 Page 36: In the third display, a factor of [math]\tau(q_0r)^{O(1)}[/math] may be needed on the righthand side (but is ultimately harmless).
 Page 38: In the display after (10.14), [math]\xi(r,a;q_1,b_1;q_2,b_2;n,k)[/math] should be [math]\xi(r,a;k;q_1,b_1;q_2,b_2;n)[/math].
 Page 42: In (12.3), [math]B[/math] should probably be 2.
 Page 47: In the third display after (13.13), the condition [math]l \in {\mathcal I}_i(h)[/math] should be [math]l \in {\mathcal I}_i(sh)[/math].
 Page 49: In the top line, a comma in [math](h_1,h_2;,n_1,n_2)[/math] should be deleted.
 Page 51: In the penultimate display, one of the two consecutive commas should be deleted.
 Page 54: Three displays before (14.17), [math]\bar{r_2}(m_1+m_2)q[/math] should be [math]\bar{r_2}(m_1+m_2)/q[/math].
 Errata for MotohashiPintz's "A smoothed GPY sieve", version 1. Update: the errata below have been corrected in the most recent arXiv version of the paper.
 Page 31: The estimation of (5.14) by (5.15) does not appear to be justified. In the text, it is claimed that the second summation in (5.14) can be treated by a variant of (4.15); however, whereas (5.14) contains a factor of [math](\log \frac{R}{D})^{2\ell+1}[/math], (4.15) contains instead a factor of [math](\log \frac{R/w}{K})^{2\ell+1}[/math] which is significantly smaller (K in (4.15) plays a similar role to D in (5.14)). As such, the crucial gain of [math]\exp(k\omega/3)[/math] in (4.15) does not seem to be available for estimating the second sum in (5.14).
 Errata for Pintz's "A note on bounded gaps between primes", version 1. Update: the errata below have been corrected in subsequent versions of Pintz's paper.
 Page 7: In (2.39), the exponent of [math]3a/2[/math] should instead be [math]5a/2[/math] (it comes from dividing (2.38) by (2.37)). This impacts the numerics for the rest of the paper.
 Page 8: The "easy calculation" that the relative error caused by discarding all but the smooth moduli appears to be unjustified, as it relies on the treatment of (5.14) in MotohashiPintz which has the issue pointed out in 2.1 above.
Other relevant blog posts
 Marker lecture III: “Small gaps between primes”, Terence Tao, 19 Nov 2008.
 The GoldstonPintzYildirim result, and how far do we have to walk to twin primes ?, Emmanuel Kowalski, 22 Jan 2009.
 Number Theory News, Peter Woit, 12 May 2013.
 Bounded Gaps Between Primes, Emily Riehl, 14 May 2013.
 Bounded gaps between primes!, Emmanuel Kowalski, 21 May 2013.
 Bounded gaps between primes: some grittier details, Emmanuel Kowalski, 4 June 2013.
 Bound on prime gaps bound decreasing by leaps and bounds, Christian Perfect, 8 June 2013.
 Narrowing the Gap, Brie Finegold, AMS Blog on Math Blogs, 14 June 2013.
 Bounded gaps between primes: the dawn of (some) enlightenment, Emmanuel Kowalski, 22 June 2013.
 A ternary divisor variation, Emmanuel Kowalski, 25 June 2013.
 Conductors of onevariable transforms of trace functions, Emmanuel Kowalski, 9 September 2013.
 Polymath 8 – a Success!, Gil Kalai, 20 September 2013.
MathOverflow
 Philosophy behind Yitang Zhang’s work on the Twin Primes Conjecture, 20 May 2013.
 A technical question related to Zhang’s result of bounded prime gaps, 25 May 2013.
 How does Yitang Zhang use Cauchy’s inequality and Theorem 2 to obtain the error term coming from the [math]S_2[/math] sum, 31 May 2013.
 Tightening Zhang’s bound, 3 June 2013.
 Does Zhang’s theorem generalize to 3 or more primes in an interval of fixed length?, 3 June 2013.
Wikipedia and other references
 Bessel function
 BombieriVinogradov theorem
 BrunTitchmarsh theorem
 Dispersion method
 Prime gap
 Second HardyLittlewood conjecture
 Twin prime conjecture
Recent papers and notes
 On the exponent of distribution of the ternary divisor function, Étienne Fouvry, Emmanuel Kowalski, Philippe Michel, 11 Apr 2013.
 On the optimal weight function in the GoldstonPintzYildirim method for finding small gaps between consecutive primes, Bálint Farkas, János Pintz and Szilárd Gy. Révész, To appear in: Paul Turán Memorial Volume: Number Theory, Analysis and Combinatorics, de Gruyter, Berlin, 2013. 23 pages. arXiv
 Bounded gaps between primes, Yitang Zhang, to appear, Annals of Mathematics. Released 21 May, 2013.
 Polignac Numbers, Conjectures of Erdös on Gaps between Primes, Arithmetic Progressions in Primes, and the Bounded Gap Conjecture, Janos Pintz, 27 May 2013.
 A poor man's improvement on Zhang's result: there are infinitely many prime gaps less than 60 million, T. S. Trudgian, 28 May 2013.
 The FriedlanderIwaniec sum, É. Fouvry, E. Kowalski, Ph. Michel., May 2013.
 Notes on Zhang's prime gaps paper, Terence Tao, 1 June 2013.
 Bounded prime gaps in short intervals, Johan Andersson, 3 June 2013.
 Bounded length intervals containing two primes and an almostprime II, James Maynard, 5 June 2013.
 A note on bounded gaps between primes, Janos Pintz, 6 June 2013.
 Lower Bounds for Admissible ktuples, Avishay Tal, 15 June 2013.
 Notes in a truncated elementary Selberg sieve (Section 1, Section 2, Section 3), Janos Pintz, 18 June 2013.
 Lecture notes: bounded gaps between primes, Gergely Harcos, 1 Oct 2013.
Media
 First proof that infinitely many prime numbers come in pairs, Maggie McKee, Nature, 14 May 2013.
 Proof that an infinite number of primes are paired, Lisa Grossman, New Scientist, 14 May 2013.
 Unheralded Mathematician Bridges the Prime Gap, Erica Klarreich, Simons science news, 20 May 2013.
 The article also appeared on Wired as "Unknown Mathematician Proves Elusive Property of Prime Numbers".
 The Beauty of Bounded Gaps, Jordan Ellenberg, Slate, 22 May 2013.
 Game of proofs boosts prime pair result by millions, Jacob Aron, New Scientist, 4 June 2013.
 L'union fait la force des mathématiciens, Philippe Pajot, Le Monde, 24 June, 2013.
 Primal Madness: Mathematicians’ Hunt for Twin Prime Numbers, Amir Aczel, Discover Magazine, 10 July, 2013.
 The Twin Prime Hero, Michael Segal, Nautilus, Issue 005, 2013.
Bibliography
Additional links for some of these references (e.g. to arXiv versions) would be greatly appreciated.
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