The twin prime conjecture is one of the oldest unsolved problems in analytic number theory. There are several reasons why this conjecture remains out of reach of current techniques, but the most important obstacle is the parity problem which prevents purely sieve-theoretic methods (or many other popular methods in analytic number theory, such as the circle method) from detecting pairs of prime twins in a way that can distinguish them from other twins of almost primes. The parity problem is discussed in these previous blog posts; this obstruction is ultimately powered by the Möbius pseudorandomness principle that asserts that the Möbius function is asymptotically orthogonal to all “structured” functions (and in particular, to the weight functions constructed from sieve theory methods).

However, there is an intriguing “alternate universe” in which the Möbius function *is* strongly correlated with some structured functions, and specifically with some Dirichlet characters, leading to the existence of the infamous “Siegel zero“. In this scenario, the parity problem obstruction disappears, and it becomes possible, *in principle*, to attack problems such as the twin prime conjecture. In particular, we have the following result of Heath-Brown:

Theorem 1At least one of the following two statements are true:

- (Twin prime conjecture) There are infinitely many primes such that is also prime.
- (No Siegel zeroes) There exists a constant such that for every real Dirichlet character of conductor , the associated Dirichlet -function has no zeroes in the interval .

Informally, this result asserts that if one had an infinite sequence of Siegel zeroes, one could use this to generate infinitely many twin primes. See this survey of Friedlander and Iwaniec for more on this “illusory” or “ghostly” parallel universe in analytic number theory that should not actually exist, but is surprisingly self-consistent and to date proven to be impossible to banish from the realm of possibility.

The strategy of Heath-Brown’s proof is fairly straightforward to describe. The usual starting point is to try to lower bound

for some large value of , where is the von Mangoldt function. Actually, in this post we will work with the slight variant where is the second von Mangoldt function, and denotes Dirichlet convolution, and is an (unsquared) Selberg sieve that damps out small prime factors. This sum also detects twin primes, but will lead to slightly simpler computations. For technical reasons we will also smooth out the interval and remove very small primes from , but we will skip over these steps for the purpose of this informal discussion. (In Heath-Brown’s original paper, the Selberg sieve is essentially replaced by the more combinatorial restriction for some large , where is the primorial of , but I found the computations to be slightly easier if one works with a Selberg sieve, particularly if the sieve is not squared to make it nonnegative.)If there is a Siegel zero with close to and a Dirichlet character of conductor , then multiplicative number theory methods can be used to show that the Möbius function “pretends” to be like the character in the sense that for “most” primes near (e.g. in the range for some small and large ). Traditionally, one uses complex-analytic methods to demonstrate this, but one can also use elementary multiplicative number theory methods to establish these results (qualitatively at least), as will be shown below the fold.

The fact that pretends to be like can be used to construct a tractable approximation (after inserting the sieve weight ) in the range (where for some large ) for the second von Mangoldt function , namely the function

Roughly speaking, we think of the periodic function and the slowly varying function as being of about the same “complexity” as the constant function , so that is roughly of the same “complexity” as the divisor function which is considerably simpler to obtain asymptotics for than the von Mangoldt function as the Möbius function is no longer present. (For instance, note from the Dirichlet hyperbola method that one can estimate to accuracy with little difficulty, whereas to obtain a comparable level of accuracy for or is essentially the Riemann hypothesis.)One expects to be a good approximant to if is of size and has no prime factors less than for some large constant . The Selberg sieve will be mostly supported on numbers with no prime factor less than . As such, one can hope to approximate (1) by the expression

as it turns out, the error between this expression and (1) is easily controlled by sieve-theoretic techniques. Let us ignore the Selberg sieve for now and focus on the slightly simpler sum As discussed above, this sum should be thought of as a slightly more complicated version of the sum Accordingly, let us look (somewhat informally) at the task of estimating the model sum (3). One can think of this problem as basically that of counting solutions to the equation with in various ranges; this is clearly related to understanding the equidistribution of the hyperbola in . Taking Fourier transforms, the latter problem is closely related to estimation of the Kloosterman sums where denotes the inverse of in . One can then use the Weil bound where is the greatest common divisor of (with the convention that this is equal to if vanish), and the decays to zero as . The Weil bound yields good enough control on error terms to estimate (3), and as it turns out the same method also works to estimate (2) (provided that with large enough).Actually one does not need the full strength of the Weil bound here; any power savings over the trivial bound of will do. In particular, it will suffice to use the weaker, but easier to prove, bounds of Kloosterman:

Lemma 2 (Kloosterman bound)One has whenever and are coprime to , where the is with respect to the limit (and is uniform in ).

*Proof:* Observe from change of variables that the Kloosterman sum is unchanged if one replaces with for . For fixed , the number of such pairs is at least , thanks to the divisor bound. Thus it will suffice to establish the fourth moment bound

We will also need another easy case of the Weil bound to handle some other portions of (2):

Lemma 3 (Easy Weil bound)Let be a primitive real Dirichlet character of conductor , and let . Then

*Proof:* As is the conductor of a primitive real Dirichlet character, is equal to times a squarefree odd number for some . By the Chinese remainder theorem, it thus suffices to establish the claim when is an odd prime. We may assume that is not divisible by this prime , as the claim is trivial otherwise. If vanishes then does not vanish, and the claim follows from the mean zero nature of ; similarly if vanishes. Hence we may assume that do not vanish, and then we can normalise them to equal . By completing the square it now suffices to show that

While the basic strategy of Heath-Brown’s argument is relatively straightforward, implementing it requires a large amount of computation to control both main terms and error terms. I experimented for a while with rearranging the argument to try to reduce the amount of computation; I did not fully succeed in arriving at a satisfactorily minimal amount of superfluous calculation, but I was able to at least reduce this amount a bit, mostly by replacing a combinatorial sieve with a Selberg-type sieve (which was not needed to be positive, so I dispensed with the squaring aspect of the Selberg sieve to simplify the calculations a little further; also for minor reasons it was convenient to retain a tiny portion of the combinatorial sieve to eliminate extremely small primes). Also some modest reductions in complexity can be obtained by using the second von Mangoldt function in place of . These exercises were primarily for my own benefit, but I am placing them here in case they are of interest to some other readers.

** — 1. Consequences of a Siegel zero — **

It is convenient to phrase Heath-Brown’s theorem in the following equivalent form:

Theorem 4Suppose one has a sequence of real Dirichlet characters of conductor going to infinity, and a sequence of real zeroes with as . Then there are infinitely many prime twins.

Henceforth, we omit the dependence on from all of our quantities (unless they are explicitly declared to be “fixed”), and the asymptotic notation , , , etc. will always be understood to be with respect to the parameter, e.g. means that for some fixed . (In the language of this previous blog post, we are thus implicitly using “cheap nonstandard analysis”, although we will not explicitly use nonstandard analysis notation (other than the asymptotic notation mentioned above) further in this post. With this convention, we now have a single (but not fixed) Dirichlet character of some conductor with a Siegel zero

It will also be convenient to use the crude bound which can be proven by elementary means (see e.g. Exercise 57 of this post), although one can use Siegel’s theorem to obtain the better bound . Standard arguments (see also Lemma 59 of this blog post) then giveWe now use this Siegel zero to show that pretends to be like for primes that are comparable (in log-scale) to :

Lemma 5For any fixed , we have

For more precise estimates on the error, see the paper of Heath-Brown (particularly Lemma 3).

*Proof:* It suffices to show, for sufficiently large fixed , that

We begin by considering the sum

for some large (which we will eventually take to be a power of ); we will exploit the fact that this sum is very stable for comparable to in log-scale. By the Dirichlet hyperbola method, we can write this as Since , one can show through summation by parts (see Lemma 71 of this previous post) that for any , while from the integral test (see Lemma 2 of this previous post) we have We can thus estimate (9) as From summation by parts we again have and we have the crude bound so by using (7) and we arrive at for any , where the exponent does not depend on . In particular, if and is large enough, then by (6), (7), (8) we have Setting and and subtracting, we conclude that On the other hand, observe that is always non-negative, and that whenever and , with primes with . Since any number with has at most representations of the form with and , and no outside of the range has such a representation, we thus see that Comparing this with (10), we conclude that since , the claim follows.

** — 2. Main argument — **

We let be a large absolute constant ( will do) and set to be the primorial of . Set for some large fixed (large compared to or ). Let be a smooth non-negative function supported on and equal to at . Set

and Thus is a smooth cutoff to the region , and is a smooth cutoff to the region . It will suffice to establish the lower bound because the non-twin primes contribute at most to the left-hand side. The weight is an unsquared Selberg sieve designed to damp out those for which or have somewhat small prime factors; we did not square this weight as is customary with the Selberg sieve in order to simplify the calculations slightly (the fact that the weight can be non-negative sometimes will not be a serious concern for us). Thus is non-negative, and supported on those products of primes with and , times a square. Convolving (11) by and using the identity , we have where . (The quantities are all non-negative, but we will not take advantage of these facts here.) It thus suffices to establish the two bounds and the intuition here is that Lemma 5 is showing that is “sparse” and so the contribution of should be relatively small.We begin with (13). Let be a small fixed quantity to be chosen later. Observe that if is non-zero, then must have a factor on which is non-zero, which implies that is either divisible by a prime with , or by the square of a prime. If the former case occurs, then either or is divisible by ; since , this implies that either is divisible by a prime with , or that is divisible by a prime less than . To summarise, at least one of the following three statements must hold:

- is divisible by a prime .
- is divisible by the square of a prime .
- is divisible by a prime with .

It thus suffices to establish the estimates

and as the claim then follows by summing and sending slowly to zero.We begin with (15). Observe that if divides then either divides or divides . In particular the number of with is . The summand is by the divisor bound, so the left-hand side of (15) is bounded by

and the claim follows.Next we turn to (14). We can very crudely bound

so it suffices to show that By Mertens’ theorem, it suffices to show that for all .We use a modification of the argument used to prove Proposition 4.2 of this Polymath8b paper. By Fourier inversion, we may write

for some rapidly decreasing function , so that and hence and hence by the triangle inequality for any fixed . Since , we can thus (after substituting ) bound the left-hand side of (18) by and so it will suffice to show the bound for any and .We factor where are primes, and then write where and is the largest index for which . Clearly and with , and the least prime factor of is such that

we have on the support of , and so and thus . Clearly we haveWe write , where denotes the number of prime factors of counting multiplicity. We can thus bound the left-hand side of (19) by

We may replace the weight with a restriction of to the interval . The constraint removes two residue classes modulo every odd prime less than , while the constraint restricts to residue classes modulo . Standard sieve theory then gives and so we are reduced to showing that Factoring , we can bound the left-hand side by which (for large enough) is bounded by which by Mertens’ theorem is bounded by and the claim follows.For future reference we observe that the above arguments also establish the bound

and (if one replaces with ) for all .Finally, we turn to (16). Using (17) again, it suffices to show that

The claim then follows from (21) and Lemma 5.It remains to prove (12), which we write as

On the support of , we can write The contribution of the error term can be bounded by applying (20), this is bounded by which is acceptable for large enough. Thus it suffices to show that which we write as where . We split where , , are smooth truncations of to the intervals , , and respectively. It will suffice to establish the bounds We begin with (24), which is a relatively easy consequence of the cancellation properties of . We may rewrite the left-hand side as The summand vanishes unless , , and is coprime to , so that . For fixed , the constraints , restricts to residue classes of the form , with , in particular and for some with . Let us fix and consider the sum Writing , this becomes From Lemma 3, we have since is coprime to . From summation by parts we thus have (noting that if is large enough) and so we can bound the left-hand side of (24) in magnitude by and (24) follows.Now we prove (23), which is where we need nontrivial bounds on Kloosterman sums. Expanding out and using the triangle inequality, it suffices (for large enough) to show that

for all . By Fourier expansion of the and constraints (retaining only the restriction that is odd), it suffices to show that for every .Fix . If for an odd , then we can uniquely factor such that , , and . It thus suffices to show that

Actually, we may delete the condition since this is implied by the constraints and odd.We first dispose of the case when is large in the sense that . Making the change of variables , we may rewrite the left-hand side as

We can assume is coprime to and odd with coprime to and , as the contribution of all other cases vanish. The constraints that is odd and then restricts to a single residue class modulo , with restricted to a single residue class modulo . We split this into residue classes modulo to make the phase constant on each residue class. The modulus is not divisible by , since is coprime to and . As such, has mean zero on every consecutive elements in each residue class modulo under consideration, and from summation by parts we then have and hence the contribution of the case to (25) is which is acceptable.It remains to control the contribution of the case to (25). By the triangle inequality, it suffices to show that

for all coprime to . We can of course restrict to be coprime to each other and to . Writing , the constraint is equivalent to and so we can rewrite the left-hand side as By Fourier expansion, we can write as a linear combination of with bounded coefficients and , so it suffices to show that Next, by Fourier expansion of the constraint , we write the left-hand side as From Poisson summation and the smoothness of , we see that the inner sum is unless for some integer , where denotes the distance from to the nearest integer. The contribution of the which do not satisfy this relation is easily seen to be acceptable. From the support of we see in particular that there are only remaining choices for . Thus it suffices by the triangle inequality to show that for each of the form (26).We rearrange the left-hand side as

Suppose first that is of the form for some integer . Then the phase is periodic with period and has mean zero here (since ). From this, we can estimate the inner sum by ; since is restricted to be of size , this contribution is certainly acceptable. Thus we may assume that is not of the form . A similar argument works when (say), so we may assume that , so that .

By (26), this forces the denominator of in lowest form to be . By Lemma 2, we thus have

for any , so from Poisson summation we have since is constrained to be , the claim follows.Finally, we prove (22), which is a routine sieve-theoretic calculation. We rewrite the left-hand side as

The summand vanishes unless are coprime to with and . From Poisson summation one then has The error term is certainly negligible, so it suffices to show that We can control the left-hand side by Fourier analysis. Writing and for some rapidly decreasing functions , the left-hand side may be expressed as which factors as where for , and for . From Mertens’ theorem we have the crude bound which by the rapid decrease of allows one to restrict to the range with an error of . In particular, we now have .Recalling that

for , we can factor where (the restriction being to prevent vanishing for and small) and one has for , and and for odd . In particular, from the Cauchy integral formula we see that for . Since we also have in this region, we thus can write (27) as and our task is now to show that We have when (even when have negative real part); since , we conclude from the Cauchy integral formula that when . For the remaining primes , we have when and . Summing in using Lemma 5 to handle those between and , and Mertens’ theorem and the trivial bound for all other , we conclude that and thus From this and the rapid decrease of , we may restrict the range of even further to for any that goes to infinity arbitrarily slowly with . For sufficiently slow , the above estimates on and Lemma 5 (now used to handle those between and for some going sufficiently slowly to zero) give and so we are reduced to establishing that We may once again use the rapid decrease of to remove the prefactor as well as the restrictions , and reduce to showing that For large enough, it will suffice to show that with the implied constant independent of . But the left-hand side evaluates to , and the claim follows.

## 40 comments

Comments feed for this article

26 August, 2015 at 10:59 pm

AnonymousIs there any known probabilistic argument for the existence/ nonexistence of Siegel zeros?

27 August, 2015 at 8:08 am

Terence TaoProbabilistic arguments (in particular, the Mobius pseudorandomness principle, discussed in this previous post) suggest that the generalised Riemann Hypothesis (GRH) is true, which can be viewed as the polar opposite of having a Siegel zero (certainly the two statements are incompatible). As such, the Siegel zero problem is really quite tantalising; it is the strongest surviving alternative to the conjectural picture we have about the distribution of the primes, and eliminating it would be viewed as a significant advance towards the GRH (although there would still be a lot further to go to finish that off entirely). (Historically, there were GRH alternatives that were even stronger than the Siegel zero, such as the “tenth discriminant”, but these at least have been eliminated, though not without quite a bit of effort.)

4 September, 2015 at 4:31 am

SergeiIt is an interesting idea to use an unsquared Selberg sieve.

In fact, on the generalized Elliott-Halberstam conjecture

an unsquared Selberg sieve weight does correlate with the MÃ¶bius function,

and this can be used to deduce the twin prime conjecture from

the generalized Elliott-Halberstam conjecture.

The idea is to use the unsquared sieve weight

where is the indicator function of and is the set of squarefree integers

which have exactly prime factors.

Now assume the generalized Elliott-Halberstam conjecture, and let be a real number to be chosen later.

Define the function to be when is positive, and otherwise.

Take

Consider the weighted expression

where

Using Theorems 3.5, 3.6 of Polymath8b, it can be shown that

for fixed if is close enough to .

(note that integers for which or has a small prime factor give negligible contribution).

According to Chapter 16 of Friedlander-Iwaniec, if there are no pairs prime, prime, then

has a completely determined distribution function, so we can compute that

where as .

Choosing close enough to ,

we get and hence

has a nonzero distribution function, and again by Chapter 16 of Friedlander-Iwaniec

it follows that

has a nonzero distribution function.

4 September, 2015 at 7:22 am

Terence TaoI think that if you do the calculations carefully (in particular paying attention to the main terms that are not directly treatable by GEH, coming from convolutions in which one factor is supported very close to the origin or which otherwise fails to obey a Siegel-Walfisz condition), you will find that converges to I, not to 0, as .

For the twin prime problem, even with GEH, one has the parity problem scenario in which for all (or almost all) for which are almost prime (here is the Liouville function, not the sieve weight). In this scenario there are essentially no twin primes (since for such primes one has ), and your weight is essentially equal to 1. This scenario is consistent with GEH (assuming Mobius pseudorandomness) and with all other known inputs available to sieve theory, including those in Friedlander-Iwaniec. From the work of Bomberi we know that (on EH) this scenario is essentially the only scenario in which we have essentially no twin primes.

Personally, I advise against spending too much time on trying to attack the twin prime conjecture under hypotheses such as GEH unless you can pinpoint the precise input you are using (or hope to use) which breaks the parity barrier by being incompatible (at least from a heuristic, moral, or conjectural standpoint) with the scenario. (For instance, in the current blog post it is Lemma 3 which is providing the incompatibility, because the Siegel zero forces to behave like on almost primes, and Lemma 3 (plus some sieve theory) precludes the scenario on such almost primes.)

4 September, 2015 at 10:42 pm

SergeiYes, the weight is essentially equal to in this unique scenario, but in this scenario the unsquared weight is essentially equal to on the primes for which . It is different from the weight in the squared Selberg sieve, which is NOT essentially equal to in this case?

4 September, 2015 at 11:05 pm

Terence TaoActually, I don’t think is all that small on those primes for which (note that will likely have some prime factors less than ; this is a subtlety that also shows up in Bombieri’s analysis… one can insert a further sieve to eliminate extremely small prime factors, but not factors of size near unless one damps the function to a higher order near ). Indeed, Mobius pseudorandomness heuristics predict that will be asymptotically orthogonal to (whether one restricts to be prime or not) and so the value of should have essentially no influence on the behaviour of .

To repeat my previous comment, the parity problem is not an obstacle to be taken lightly. If you haven’t identified a precise input in your argument which is explicitly getting around the parity barrier (basically, one needs to somehow control a sum of an expression that has a nontrivial correlation with , which none of the standard sieve weights do even when weighted by or ), the chances are overwhelmingly likely that there is going to be an error in your analysis.

5 September, 2015 at 10:59 pm

SergeiI absolutely agree that the parity barrier is a very serious problem. It is not entirely clear where is the moral difference between the 2-dimensional weights

where

and

where

I don’t quite see how could be large when has one (say) prime factor less than . But it is clear that could be large when has one prime factor less than .

6 September, 2015 at 10:02 am

Terence TaoNote that factors as , where . Next, since

we can write

which on replacing by is essentially (assuming squarefree and close to for simplicity)

If , the latter term is roughly speaking like restricted to those numbers that are -rough (have no prime factors much smaller than ). This latter set of numbers is larger than the set of primes by a factor of about . So, while is of size about 1 on primes, it is also of size about on a set of size about larger than the primes, and the net contribution of this set is of equal strength (in an L^1 sense) to the contribution on primes. (It may be small in an sense, but it is the size which is the most relevant for these computations.) For instance, it is an instructive exercise to compute and find out that this is rather small (as is predicted from the Mobius pseudorandomness principle – has to give an equal weight to numbers with an odd number of prime factors, and numbers with an even number of prime factors), even though the contribution coming from the primes (or even from all of the numbers with all prime factors larger than ) is quite large.

Returning to , we now see that can be somewhat large (of size about ) when the smallest prime factor of is comparable to , and the contribution of this case to the in your original argument is of about the same size as the contribution of the case when is prime, which I believe will ultimately lead to converging to I rather than to 0 as I said in my first comment (this is the only possible limiting value for which is compatible with the Mobius pseudorandomness principle). In any event, it’s probably a good idea for you to work out the computation of in full detail.

—

By the way, here is a more explicit way to think about the parity obstruction for twin primes which may help you appreciate why the inputs you are using are not strong enough to give the conclusion you wish to obtain. Sieve theory relies on inputs that can take the form of upper or lower bounds on sums of arithmetic functions, e.g.

or

or

,

(for some main terms and error magnitude , and various arithmetic functions , which may for instance be the restriction of some other arithmetic function, e.g. or , to a residue class ) or on averaged bounds such as Elliott-Halberstam type bounds

Sieve theory also takes as input pointwise inequalities

between arithmetic functions (e.g. the trivial bounds ).

The whole game of sieve theory is to try to cleverly take linear combinations of these inputs, weighted by suitable sieves, to ultimately deduce something like

or perhaps

where the main term is significantly larger than the error term .

Call an estimate

parity-insensitiveif it is conjectured that the estimate is essentially unchanged after weighting the natural numbers by the weight . For instance, Elliott-Halberstam type bounds on are conjectured (by the Mobius pseudorandomness heuristic) to also hold for the weighted sum ; similarly if is replaced by . Clearly any pointwise bound is also parity-insensitive since the weight is non-negative. In factallof the standard inputs to sieve theory (including GEH) are conjectured to be parity-insensitive. On the other hand, bounds such as (1) or (2) are parity-sensitive (and the bounds you claim would also be parity sensitive if converged to any value other than I), because the weight vanishes on twin primes. It is also clear that taking linear combinations of parity-insensitive inequalities weighted by sieve weights can only ever yield more parity-insensitive inequalities, no matter how cleverly one chooses the sieve weights and the linear combinations. As such, it is not possible to produce twin primes by sieve theoretic arguments, unless one uses an input that is parity sensitive, or if one is operating under a hypothesis (such as a Siegel zero hypothesis) that is incompatible with the Mobius pseudorandomness heuristic. If you are unable to identify the precise parity sensitive input or pseudorandomness-violating hypothesis in your argument, this is a very strong signal that your argument is not correct.6 September, 2015 at 11:10 pm

SergeiThanks for this! Very enlightening.

7 September, 2015 at 5:15 am

SergeiIs it right that it is unclear what happens with the asymptotic for in the intermediate regime for various going to as ?

7 September, 2015 at 8:19 am

Terence TaoDepends on what you are trying to compute. A plain sum such as should still be computable because the constant function is extremely well distributed in arithmetic progressions. However a sum such as becomes very tricky, it involves understanding the distribution of in arithmetic progressions of spacing up to and it is known that the Elliott-Halberstam conjecture breaks down for sufficiently close to 1, see the work of Friedlander and Granville. It may still be possible to use a strong version of pseudorandomness hypotheses though (e.g. Montgomery’s conjecture on the error term in the prime number theorem in arithmetic progressions) to predict what happens. Of course in the limit , is essentially the von Mangoldt function, which is sensitive to in contrast to the cases, so there must be some transition behaviour at some point.

27 August, 2015 at 8:08 am

WillYes, the heuristic that the primes are distributed randomly (e.g. the Cramer model) suggests that the error term for the prime number theorem in arithmetic progressions is , which implies no Siegel zeros.

27 August, 2015 at 10:24 am

David SpeyerMinor suggestion: Friedlander and Iwaniec is available freely and legally online http://www.ams.org/notices/200907/rtx090700817p.pdf , but your link requires MathSciNet access. You might want to switch to the free one.

[Link changed, thanks – T.]27 August, 2015 at 11:13 am

David SpeyerBy the way, I’d enjoy a blogpost laying out what the alternative “ghostly” world looks like. I’ve picked it up in bits and pieces from your posts on the parity problem and other sources, but it would be interesting to see it all in one place, laid out as a consistent alternative.

28 August, 2015 at 8:51 am

meditationataeI find it very stimulating that you write about this “unlikely” “alternate universe”. I can recognize terminology (e.g. “damping” ) used in sieve theory, that is also common in electronic filter terminology (signal processing). Is this semblance of an analogy between filters and sieves worthy of some consideration by students or non-specialists of analytic number theory?

31 August, 2015 at 3:05 am

AnonymousIt is interesting to observe that the (hypothetical) asymptotic orthogonality of the Mobius function to all “structured” functions does not contradict the fact that has bounded algorithmic complexity.

31 August, 2015 at 5:27 am

meditationataeIt was my first encounter with Heath-Brown’s theorem. I’d like to know if there are heuristics or other things that give hope to analytic number theorists concerning which of (a) Twin Prime Conjecture, or (b) “No Siegel zeros”, “should” be the least difficult to prove?

1 September, 2015 at 5:02 pm

John MangualThe points on the hyperbola look equidistributed to me. How is this connected to Möbius pseudorandomness?

5 September, 2015 at 7:39 am

AnonymousAre there some general rules to design a sieve (which motivate the design of the multidimensional Selberg sieve and its variants)?

8 September, 2015 at 2:33 am

Boris Sklyar“MATRIX DEFINITION” OF PRIME NUMBERS:

There are two 2-dimensional arrays:

……………………………|5 10 15 20 ..|

6i^2-1+(6i-1)(j-1)=…..|23 34 45 56…|

……………………………|53 70 87 104…|

…………………………..|95 118 141 164…|

…………………………..|149 178 207 236…|

…………………………..|… … … … |

…………………………….| 5 12 19 26 ..|

6i^2-1+(6i+1)(j-1) =….|23 36 49 62…|

…………………………….|53 72 91 110…|

……………………………..|95 120 145 170…|

……………………………..|149 180 211 242…|

……………………………|… … … … |

Positive integers not contained in these arrays are indexes p of all prime numbers in the sequence S1(p)=6p+5, i.e. p=0, 1, 2, 3, 4, , 6, 7, 8, 9, , 11, , 13, 14, , 16, 17, 18, , , 21, 22, , 24, , , 27, 28, 29, …

and primes are: 5, 11, 17. 23, 29, , 41, 47, 53, 59, , 71, , 83, 89, , 101, 107, 113, , , 131, 137, , 149, , , 167, 173, 179, ….

There are two 2-dimensional arrays:

………………………………. |3 8 13 18 ..|

6i^2-1-2i+(6i-1)(j-1)=….. |19 30 41 52…|

…………………………………|47 64 81 98…|

…………………………………|87 110 133 156…|

…………………………………|139 168 197 226…|

…………………………………|… … … … |

……………………………….. | 7 14 21 28 ..|

6i^2-1+2i+(6i+1)(j-1)=…..|27 40 53 66…|

………………………………….|59 78 97 116..|

………………………………….|103 128 153 178..|

………………………………….|159 190 221 252..|

………………………………….|… … … … … |

Positive integers not contained in these arrays are indexes p of all prime numbers in the sequence S2(p)=6p+7, i.e. p=0, 1, 2, , 4, 5, 6, , , 9, 10, 11, 12, , , 15 , 16, 17, , , 20, , 22, , 24, 25 , 26, , , 29, …

and primes are: 7, 13, 19. , 31, 37, 43, , , 61, 67, 73, 79, , , 97, 103, 109, , , 127, , 139, , 151, 157, 163, , , 181 ….

,

http://ijmcr.in/index.php/current-issue/86-title-matrix-sieve-new-algorithm-for-finding-prime-numbers

http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=13752&lngWId=3

9 September, 2015 at 8:38 am

Anonymous(twin prime conjecture).

all twins prime it is the form.

; .

Always that: .

9 September, 2015 at 12:24 pm

Boris SklyarTwin primes conjecture.

N1, N2 – primes, N2-N1=2;

N1 always belongs to the sequence S1(p)=6p+5; p = 0, 1, 2, …

N2 always belongs to the sequence S2(q)=6q+7; q = 0, 1, 2, …

When p=q; N1, N2 — are twin primes.

Twin primes condition:

Odd positive integers N1 =6p+5 and N2=6p+7 are twin primes if and only if

no one of four diophantine equations has solution;

6x^2-1 + (6x -1)y=p

6x^2-1 + (6x +1)y=p

6x^2-1 – 2x+(6x -1)y=p

6x^2-1 +2x +(6x+1)y=p

x =1,2,3,..

y=0,1,2….

0 0 Rate This

12 April, 2016 at 7:53 am

AnonymousAt the start of the proof if Lemma 5, it says for each fixed natural number n. Should the n be a k?

Also, in the paragraph that starts with: We begin with (13), there is an inequality with \chi(p) between two powers of x. I believe it should be p, as that is what is used in later lines.

[Corrected, thanks – T.]28 July, 2017 at 8:29 pm

primenumbersWe will go on to show that the distribution of prime numbers may be best visualized in two-dimensional space.

28 July, 2017 at 8:35 pm

primenumbersWe advance our analysis with the extension of division to the divisor 3in the simplifiedprime number analysis introduced earlier.

10 May, 2019 at 8:37 am

The alternative hypothesis for unitary matrices | What's new[…] which differs from (13) for any . (This fact was implicitly observed recently by Baluyot, in the original context of the zeta function.) Thus a verification of the pair correlation conjecture (17) for even a single with would rule out the alternative hypothesis. Unfortunately, such a verification appears to be on comparable difficulty with (an averaged version of) the Hardy-Littlewood conjecture, with power saving error term. (This is consistent with the fact that Siegel zeroes can cause distortions in the Hardy-Littlewood conjecture, as (implicitly) discussed in this previous blog post.) […]

28 May, 2020 at 1:43 pm

ESThe function introduced in (11) is remarked to be supported on integers whose prime factors satisfy . But if and and then . Or is the support claim only valid when square-free ?

[Corrected, thanks – T.]1 June, 2020 at 9:24 am

ESEquation (19) needs .

[Added, thanks – T.]24 June, 2020 at 11:26 am

ESIt looks like in the equation after “Standard sieve theory then gives” should contain instead of as the length of the interval is and the sieve is of dimension . I haven’t checked if this matters for later estimates.

[Corrected, thanks – T.]27 June, 2020 at 5:10 am

ESCould I please ask any minor hint about the application of summation by parts in the last step of the proof of (24)?

30 June, 2020 at 12:30 pm

Terence TaoWe are trying to sum where is the -periodic function and is the slowly varying function with . The function is supported on an interval of length (we omit the bounded factor here) and has total variation , hence by summation by parts this sum is bounded by where ranges over intervals of length . Splitting into intervals of length plus a remainder and using the bound from Lemma 3, this is and the latter term is negligible if is large enough.

10 July, 2020 at 12:13 pm

ESMany thanks!

10 July, 2020 at 12:12 pm

ESA harmless typo: the first display after is missing .

[Corrected, thanks -T.]15 July, 2020 at 3:17 pm

ESThere is something strange in the second application of Poisson’s summation formula just before the start of the proof of (22). To use the Kloosterman bound I am guessing the text suggestion is to partition in congruence classes and for each such we have a sum of (something which is essentially) over all integers which is estimated with Poisson. Because of the presence of within I think there is a problem in getting the error term claimed though. We are counting integers of size in a progression modulo and in the cases where one cannot hope to get good errors by Poisson (or otherwise?). Perhaps I am missing something?

17 July, 2020 at 6:16 pm

Terence TaoOne should perform an inverse Fourier expansion of into characters a linear combination of characters and then apply the Poisson summation formula in to the resulting sums to express things in terms of Fourier integrals such as . The cutoff is fairly harmless, it is the cutoff that provides the main contribution of , but only when is close to an integer, which basically only happens for a single choice of .

20 July, 2020 at 6:48 am

ESThank you very much for all the time and explanations so far! One last question: when the proof of (22) starts there is another Poisson summation happening. But the main term coming from the central coefficient doesn’t seem to take into account that divides . In my calculations it looks like one should have instead of . I may be missing something though. But if that is correct then the main term should behave as instead of . Again, I am sorry if this is not accurate!

20 July, 2020 at 6:42 pm

Terence TaoThere were some summations in missing in these displays that have now been corrected. The prime factorization of does not affect this summation as it is coprime to .

20 July, 2020 at 10:10 pm

ESThank you for the summations! But I was alluding to the fact that the condition should give rise to a missing term on the right-hand side of the first equation after “From Poisson summation one then has”.

21 July, 2020 at 9:43 am

Terence TaoAh, I see the issue now. The main term is indeed one power of smaller than claimed (which in retrospect was clear from probabilistic heuristics such as the Cramer model), and all the error bounds have to be improved by a factor of accordingly. In fact now that I see it I had wasted a factor of anyway in the proof of (19) so the two errors ended up cancelinc each other out. The post has now been updated with the correct powers of $\log x$ and other appropriate changes.

15 September, 2021 at 11:10 am

The Hardy–Littlewood–Chowla conjecture in the presence of a Siegel zero | What's new[…] primes in the indicated range ; this bound is non-trivial for as large as . (See Section 1 of this blog post for some variants of this argument, which were inspired by work of Heath-Brown.) There is also a […]