Riemann hypothesis
In mathematics, the Riemann hypothesis is a conjecture that the Riemann zeta function has its zeros only at the negative even integers and complex numbers with real part 1/2. Many consider it to be the most important unsolved problem in pure mathematics (Bombieri 2000). It is of great interest in number theory because it implies results about the distribution of prime numbers. It was proposed by Bernhard Riemann (1859), after whom it is named.
The Riemann hypothesis and some of its generalizations, along with Goldbach's conjecture and the twin prime conjecture, comprise Hilbert's eighth problem in David Hilbert's list of 23 unsolved problems; it is also one of the Clay Mathematics Institute's Millennium Prize Problems. The name is also used for some closely related analogues, such as the Riemann hypothesis for curves over finite fields.
The Riemann zeta function ζ(s) is a function whose argument s may be any complex number other than 1, and whose values are also complex. It has zeros at the negative even integers; that is, ζ(s) = 0 when s is one of −2, −4, −6, .... These are called its trivial zeros. However, the negative even integers are not the only values for which the zeta function is zero. The other ones are called non-trivial zeros. The Riemann hypothesis is concerned with the locations of these non-trivial zeros, and states that:
The real part of every non-trivial zero of the Riemann zeta function is 1/2.
Thus, if the hypothesis is correct, all the non-trivial zeros lie on the critical line consisting of the complex numbers 1/2 + i t, where t is a real number and i is the imaginary unit.
There are several nontechnical books on the Riemann hypothesis, such as (Derbyshire 2003), (Rockmore 2005), (Sabbagh 2003a, 2003b), (du Sautoy 2003), and (Watkins 2015). The books (Edwards 1974), (Patterson 1988), (Borwein Choi), (Mazur Stein) and (Broughan 2017) give mathematical introductions, while (Titchmarsh 1986), (Ivić 1985) and (Karatsuba Voronin) are advanced monographs.
Riemann zeta function
The Riemann zeta function is defined for complex s with real part greater than 1 by the absolutely convergent infinite series
- [math]\displaystyle{ \zeta(s) = \sum_{n=1}^\infty \frac{1}{n^s} = \frac{1}{1^s} + \frac{1}{2^s} + \frac{1}{3^s} + \cdots }[/math]
Leonhard Euler already considered this series in the 1730s for real values of s, in conjunction with his solution to the Basel problem. He also proved that it equals the Euler product
- [math]\displaystyle{ \zeta(s) = \prod_{p \text{ prime}} \frac{1}{1-p^{-s}}= \frac{1}{1-2^{-s}}\cdot\frac{1}{1-3^{-s}}\cdot\frac{1}{1-5^{-s}}\cdot\frac{1}{1-7^{-s}} \cdot \frac{1}{1-11^{-s}} \cdots }[/math]
where the infinite product extends over all prime numbers p.^{[1]}
The Riemann hypothesis discusses zeros outside the region of convergence of this series and Euler product. To make sense of the hypothesis, it is necessary to analytically continue the function to obtain a form that is valid for all complex s. This is permissible because the zeta function is meromorphic, so its analytic continuation is guaranteed to be unique and functional forms equivalent over their domains. One begins by showing that the zeta function and the Dirichlet eta function satisfy the relation
- [math]\displaystyle{ \left(1-\frac{2}{2^s}\right)\zeta(s) = \eta(s) = \sum_{n=1}^\infty \frac{(-1)^{n+1}}{n^s} = \frac{1}{1^s} - \frac{1}{2^s} + \frac{1}{3^s} - \cdots. }[/math]
But the series on the right converges not just when the real part of s is greater than one, but more generally whenever s has positive real part. Thus, this alternative series extends the zeta function from Re(s) > 1 to the larger domain Re(s) > 0, excluding the zeros [math]\displaystyle{ s = 1 + 2\pi in/\ln(2) }[/math] of [math]\displaystyle{ 1-2/2^s }[/math] where [math]\displaystyle{ n }[/math] is any nonzero integer (see Dirichlet eta function). The zeta function can be extended to these values too by taking limits, giving a finite value for all values of s with positive real part except for the simple pole at s = 1.
In the strip 0 < Re(s) < 1 the zeta function satisfies the functional equation
- [math]\displaystyle{ \zeta(s) = 2^s\pi^{s-1}\ \sin\left(\frac{\pi s}{2}\right)\ \Gamma(1-s)\ \zeta(1-s). }[/math]
One may then define ζ(s) for all remaining nonzero complex numbers s (Re(s) ≤ 0 and s ≠ 0) by applying this equation outside the strip, and letting ζ(s) equal the right-hand side of the equation whenever s has non-positive real part (and s ≠ 0).
If s is a negative even integer then ζ(s) = 0 because the factor sin(πs/2) vanishes; these are the trivial zeros of the zeta function. (If s is a positive even integer this argument does not apply because the zeros of the sine function are cancelled by the poles of the gamma function as it takes negative integer arguments.)
The value ζ(0) = −1/2 is not determined by the functional equation, but is the limiting value of ζ(s) as s approaches zero. The functional equation also implies that the zeta function has no zeros with negative real part other than the trivial zeros, so all non-trivial zeros lie in the critical strip where s has real part between 0 and 1.
Origin
...es ist sehr wahrscheinlich, dass alle Wurzeln reell sind. Hiervon wäre allerdings ein strenger Beweis zu wünschen; ich habe indess die Aufsuchung desselben nach einigen flüchtigen vergeblichen Versuchen vorläufig bei Seite gelassen, da er für den nächsten Zweck meiner Untersuchung entbehrlich schien.
...it is very probable that all roots are real. Of course one would wish for a rigorous proof here; I have for the time being, after some fleeting vain attempts, provisionally put aside the search for this, as it appears dispensable for the immediate objective of my investigation.
Riemann's original motivation for studying the zeta function and its zeros was their occurrence in his explicit formula for the number of primes π(x) less than or equal to a given number x, which he published in his 1859 paper "On the Number of Primes Less Than a Given Magnitude". His formula was given in terms of the related function
- [math]\displaystyle{ \Pi(x) = \pi(x) + \tfrac{1}{2} \pi(x^{\frac{1}{2}}) +\tfrac{1}{3} \pi(x^{\frac{1}{3}}) + \tfrac{1}{4}\pi(x^{\frac{1}{4}}) + \tfrac{1}{5} \pi(x^{\frac{1}{5}}) +\tfrac{1}{6}\pi(x^{\frac{1}{6}}) +\cdots }[/math]
which counts the primes and prime powers up to x, counting a prime power p^{n} as ^{1}⁄_{n}. The number of primes can be recovered from this function by using the Möbius inversion formula,
- [math]\displaystyle{ \begin{align} \pi(x) &= \sum_{n=1}^{\infty}\frac{\mu(n)}{n}\Pi(x^{\frac{1}{n}}) \\ &= \Pi(x) -\frac{1}{2}\Pi(x^{\frac{1}{2}}) - \frac{1}{3}\Pi(x^{\frac{1}{3}}) - \frac{1}{5}\Pi(x^{\frac{1}{5}}) + \frac{1}{6} \Pi(x^{\frac{1}{6}}) -\cdots, \end{align} }[/math]
where μ is the Möbius function. Riemann's formula is then
- [math]\displaystyle{ \Pi_0(x) = \operatorname{li}(x) - \sum_\rho \operatorname{li}(x^\rho) -\log(2) + \int_x^\infty\frac{dt}{t(t^2-1)\log(t)} }[/math]
where the sum is over the nontrivial zeros of the zeta function and where Π_{0} is a slightly modified version of Π that replaces its value at its points of discontinuity by the average of its upper and lower limits:
- [math]\displaystyle{ \Pi_0(x) = \lim_{\varepsilon \to 0}\frac{\Pi(x-\varepsilon) + \Pi(x+\varepsilon)}2. }[/math]
The summation in Riemann's formula is not absolutely convergent, but may be evaluated by taking the zeros ρ in order of the absolute value of their imaginary part. The function li occurring in the first term is the (unoffset) logarithmic integral function given by the Cauchy principal value of the divergent integral
- [math]\displaystyle{ \operatorname{li}(x) = \int_0^x\frac{dt}{\log(t)}. }[/math]
The terms li(x^{ρ}) involving the zeros of the zeta function need some care in their definition as li has branch points at 0 and 1, and are defined (for x > 1) by analytic continuation in the complex variable ρ in the region Re(ρ) > 0, i.e. they should be considered as Ei(ρ ln x). The other terms also correspond to zeros: the dominant term li(x) comes from the pole at s = 1, considered as a zero of multiplicity −1, and the remaining small terms come from the trivial zeros. For some graphs of the sums of the first few terms of this series see (Riesel Göhl) or (Zagier 1977).
This formula says that the zeros of the Riemann zeta function control the oscillations of primes around their "expected" positions. Riemann knew that the non-trivial zeros of the zeta function were symmetrically distributed about the line s = 1/2 + it, and he knew that all of its non-trivial zeros must lie in the range 0 ≤ Re(s) ≤ 1. He checked that a few of the zeros lay on the critical line with real part 1/2 and suggested that they all do; this is the Riemann hypothesis.
Consequences
The practical uses of the Riemann hypothesis include many propositions known true under the Riemann hypothesis, and some that can be shown to be equivalent to the Riemann hypothesis.
Distribution of prime numbers
Riemann's explicit formula for the number of primes less than a given number in terms of a sum over the zeros of the Riemann zeta function says that the magnitude of the oscillations of primes around their expected position is controlled by the real parts of the zeros of the zeta function. In particular the error term in the prime number theorem is closely related to the position of the zeros. For example, if β is the upper bound of the real parts of the zeros, then (Ingham 1932)^{:Theorem 30, p.83}, (Montgomery Vaughan)^{:p. 430}
- [math]\displaystyle{ \pi(x) - \operatorname{li}(x) = O \left( x^{\beta} \log x \right) }[/math].
It is already known that 1/2 ≤ β ≤ 1 (Ingham 1932).^{:p. 82}
Von Koch (1901) proved that the Riemann hypothesis implies the "best possible" bound for the error of the prime number theorem. A precise version of Koch's result, due to (Schoenfeld 1976), says that the Riemann hypothesis implies
- [math]\displaystyle{ |\pi(x) - \operatorname{li}(x)| \lt \frac{1}{8\pi} \sqrt{x} \log(x), \qquad \text{for all } x \ge 2657, }[/math]
where π(x) is the prime-counting function, and log(x) is the natural logarithm of x.
(Schoenfeld 1976) also showed that the Riemann hypothesis implies
- [math]\displaystyle{ |\psi(x) - x| \lt \frac{1}{8\pi} \sqrt{x} \log^2(x), \qquad \text{for all } x \ge 73.2, }[/math]
where ψ(x) is Chebyshev's second function.
(Dudek 2014) proved that the Riemann hypothesis implies that for all [math]\displaystyle{ x \geq 2 }[/math] there is a prime [math]\displaystyle{ p }[/math] satisfying
- [math]\displaystyle{ x - \frac{4}{\pi} \sqrt{x} \log x \lt p \leq x }[/math].
This is an explicit version of a theorem of Cramér.
Growth of arithmetic functions
The Riemann hypothesis implies strong bounds on the growth of many other arithmetic functions, in addition to the primes counting function above.
One example involves the Möbius function μ. The statement that the equation
- [math]\displaystyle{ \frac{1}{\zeta(s)} = \sum_{n=1}^\infty \frac{\mu(n)}{n^s} }[/math]
is valid for every s with real part greater than 1/2, with the sum on the right hand side converging, is equivalent to the Riemann hypothesis. From this we can also conclude that if the Mertens function is defined by
- [math]\displaystyle{ M(x) = \sum_{n \le x} \mu(n) }[/math]
then the claim that
- [math]\displaystyle{ M(x) = O\left(x^{\frac{1}{2}+\varepsilon}\right) }[/math]
for every positive ε is equivalent to the Riemann hypothesis (J.E. Littlewood, 1912; see for instance: paragraph 14.25 in (Titchmarsh 1986)). (For the meaning of these symbols, see Big O notation.) The determinant of the order n Redheffer matrix is equal to M(n), so the Riemann hypothesis can also be stated as a condition on the growth of these determinants. The Riemann hypothesis puts a rather tight bound on the growth of M, since (Odlyzko te Riele) disproved the slightly stronger Mertens conjecture
- [math]\displaystyle{ |M(x)| \le \sqrt x. }[/math]
The Riemann hypothesis is equivalent to many other conjectures about the rate of growth of other arithmetic functions aside from μ(n). A typical example is Robin's theorem (Robin 1984), which states that if σ(n) is the divisor function, given by
- [math]\displaystyle{ \sigma(n) = \sum_{d\mid n} d }[/math]
then
- [math]\displaystyle{ \sigma(n) \lt e^\gamma n \log \log n }[/math]
for all n > 5040 if and only if the Riemann hypothesis is true, where γ is the Euler–Mascheroni constant.
Another example was found by Jérôme Franel, and extended by Landau (see (Franel Landau)). The Riemann hypothesis is equivalent to several statements showing that the terms of the Farey sequence are fairly regular. One such equivalence is as follows: if F_{n} is the Farey sequence of order n, beginning with 1/n and up to 1/1, then the claim that for all ε > 0
- [math]\displaystyle{ \sum_{i=1}^m|F_n(i) - \tfrac{i}{m}| = O(n^{\frac{1}{2}+\epsilon}) }[/math]
is equivalent to the Riemann hypothesis. Here
- [math]\displaystyle{ m = \sum_{i=1}^n\phi(i) }[/math]
is the number of terms in the Farey sequence of order n.
For an example from group theory, if g(n) is Landau's function given by the maximal order of elements of the symmetric group S_{n} of degree n, then (Massias Nicolas) showed that the Riemann hypothesis is equivalent to the bound
- [math]\displaystyle{ \log g(n) \lt \sqrt{\operatorname{Li}^{-1}(n)} }[/math]
for all sufficiently large n.
Lindelöf hypothesis and growth of the zeta function
The Riemann hypothesis has various weaker consequences as well; one is the Lindelöf hypothesis on the rate of growth of the zeta function on the critical line, which says that, for any ε > 0,
- [math]\displaystyle{ \zeta\left(\frac{1}{2} + it\right) = O(t^\varepsilon), }[/math]
as [math]\displaystyle{ t \to \infty }[/math].
The Riemann hypothesis also implies quite sharp bounds for the growth rate of the zeta function in other regions of the critical strip. For example, it implies that
- [math]\displaystyle{ e^\gamma\le \limsup_{t\rightarrow +\infty}\frac{|\zeta(1+it)|}{\log\log t}\le 2e^\gamma }[/math]
- [math]\displaystyle{ \frac{6}{\pi^2}e^\gamma\le \limsup_{t\rightarrow +\infty}\frac{1/|\zeta(1+it)|}{\log\log t}\le \frac{12}{\pi^2}e^\gamma }[/math]
so the growth rate of ζ(1+it) and its inverse would be known up to a factor of 2 (Titchmarsh 1986).
Large prime gap conjecture
The prime number theorem implies that on average, the gap between the prime p and its successor is log p. However, some gaps between primes may be much larger than the average. Cramér proved that, assuming the Riemann hypothesis, every gap is O(√p log p). This is a case in which even the best bound that can be proved using the Riemann hypothesis is far weaker than what seems true: Cramér's conjecture implies that every gap is O((log p)^{2}), which, while larger than the average gap, is far smaller than the bound implied by the Riemann hypothesis. Numerical evidence supports Cramér's conjecture (Nicely 1999).
Analytic criteria equivalent to the Riemann hypothesis
Many statements equivalent to the Riemann hypothesis have been found, though so far none of them have led to much progress in proving (or disproving) it. Some typical examples are as follows. (Others involve the divisor function σ(n).)
The Riesz criterion was given by (Riesz 1916), to the effect that the bound
- [math]\displaystyle{ -\sum_{k=1}^\infty \frac{(-x)^k}{(k-1)! \zeta(2k)}= O\left(x^{\frac{1}{4}+\epsilon}\right) }[/math]
holds for all ε > 0 if and only if the Riemann hypothesis holds.
(Nyman 1950) proved that the Riemann hypothesis is true if and only if the space of functions of the form
- [math]\displaystyle{ f(x) = \sum_{\nu=1}^nc_\nu\rho \left(\frac{\theta_\nu}{x} \right) }[/math]
where ρ(z) is the fractional part of z, 0 ≤ θ_{ν} ≤ 1, and
- [math]\displaystyle{ \sum_{\nu=1}^nc_\nu\theta_\nu=0 }[/math],
is dense in the Hilbert space L^{2}(0,1) of square-integrable functions on the unit interval. (Beurling 1955) extended this by showing that the zeta function has no zeros with real part greater than 1/p if and only if this function space is dense in L^{p}(0,1)
(Salem 1953) showed that the Riemann hypothesis is true if and only if the integral equation
- [math]\displaystyle{ \int_{0}^\infty\frac{z^{-\sigma-1}\phi(z)}{{e^{x/z}}+1}\,dz=0 }[/math]
has no non-trivial bounded solutions [math]\displaystyle{ \phi }[/math] for [math]\displaystyle{ 1/2\lt \sigma \lt 1 }[/math].
Weil's criterion is the statement that the positivity of a certain function is equivalent to the Riemann hypothesis. Related is Li's criterion, a statement that the positivity of a certain sequence of numbers is equivalent to the Riemann hypothesis.
(Speiser 1934) proved that the Riemann hypothesis is equivalent to the statement that [math]\displaystyle{ \zeta'(s) }[/math], the derivative of [math]\displaystyle{ \zeta(s) }[/math], has no zeros in the strip
- [math]\displaystyle{ 0 \lt \Re(s) \lt \frac12. }[/math]
That [math]\displaystyle{ \zeta(s) }[/math] has only simple zeros on the critical line is equivalent to its derivative having no zeros on the critical line.
The Farey sequence provides two equivalences, due to Jerome Franel and Edmund Landau in 1924.
Consequences of the generalized Riemann hypothesis
Several applications use the generalized Riemann hypothesis for Dirichlet L-series or zeta functions of number fields rather than just the Riemann hypothesis. Many basic properties of the Riemann zeta function can easily be generalized to all Dirichlet L-series, so it is plausible that a method that proves the Riemann hypothesis for the Riemann zeta function would also work for the generalized Riemann hypothesis for Dirichlet L-functions. Several results first proved using the generalized Riemann hypothesis were later given unconditional proofs without using it, though these were usually much harder. Many of the consequences on the following list are taken from (Conrad 2010).
- In 1913, Grönwall showed that the generalized Riemann hypothesis implies that Gauss's list of imaginary quadratic fields with class number 1 is complete, though Baker, Stark and Heegner later gave unconditional proofs of this without using the generalized Riemann hypothesis.
- In 1917, Hardy and Littlewood showed that the generalized Riemann hypothesis implies a conjecture of Chebyshev that
- [math]\displaystyle{ \lim_{x\to 1^-}\sum_{p\gt 2}(-1)^{(p+1)/2}x^p=+\infty, }[/math]
- which says that primes 3 mod 4 are more common than primes 1 mod 4 in some sense. (For related results, see Prime number theorem § Prime number race.)
- In 1923 Hardy and Littlewood showed that the generalized Riemann hypothesis implies a weak form of the Goldbach conjecture for odd numbers: that every sufficiently large odd number is the sum of three primes, though in 1937 Vinogradov gave an unconditional proof. In 1997 Deshouillers, Effinger, te Riele, and Zinoviev showed that the generalized Riemann hypothesis implies that every odd number greater than 5 is the sum of three primes. In 2013 Harald Helfgott proved the ternary Goldbach conjecture without the GRH dependence, subject to some extensive calculations completed with the help of David J. Platt.
- In 1934, Chowla showed that the generalized Riemann hypothesis implies that the first prime in the arithmetic progression a mod m is at most Km^{2}log(m)^{2} for some fixed constant K.
- In 1967, Hooley showed that the generalized Riemann hypothesis implies Artin's conjecture on primitive roots.
- In 1973, Weinberger showed that the generalized Riemann hypothesis implies that Euler's list of idoneal numbers is complete.
- (Weinberger 1973) showed that the generalized Riemann hypothesis for the zeta functions of all algebraic number fields implies that any number field with class number 1 is either Euclidean or an imaginary quadratic number field of discriminant −19, −43, −67, or −163.
- In 1976, G. Miller showed that the generalized Riemann hypothesis implies that one can test if a number is prime in polynomial time via the Miller test. In 2002, Manindra Agrawal, Neeraj Kayal and Nitin Saxena proved this result unconditionally using the AKS primality test.
- (Odlyzko 1990) discussed how the generalized Riemann hypothesis can be used to give sharper estimates for discriminants and class numbers of number fields.
- (Ono Soundararajan) showed that the generalized Riemann hypothesis implies that Ramanujan's integral quadratic form x^{2} + y^{2} + 10z^{2} represents all integers that it represents locally, with exactly 18 exceptions.
Excluded middle
Some consequences of the RH are also consequences of its negation, and are thus theorems. In their discussion of the Hecke, Deuring, Mordell, Heilbronn theorem, (Ireland Rosen) say
The method of proof here is truly amazing. If the generalized Riemann hypothesis is true, then the theorem is true. If the generalized Riemann hypothesis is false, then the theorem is true. Thus, the theorem is true!! (punctuation in original)
Care should be taken to understand what is meant by saying the generalized Riemann hypothesis is false: one should specify exactly which class of Dirichlet series has a counterexample.
Littlewood's theorem
This concerns the sign of the error in the prime number theorem. It has been computed that π(x) < li(x) for all x ≤ 10^{25} (see this table), and no value of x is known for which π(x) > li(x).
In 1914 Littlewood proved that there are arbitrarily large values of x for which
- [math]\displaystyle{ \pi(x)\gt \operatorname{li}(x) +\frac13\frac{\sqrt x}{\log x}\log\log\log x, }[/math]
and that there are also arbitrarily large values of x for which
- [math]\displaystyle{ \pi(x)\lt \operatorname{li}(x) -\frac13\frac{\sqrt x}{\log x}\log\log\log x. }[/math]
Thus the difference π(x) − li(x) changes sign infinitely many times. Skewes' number is an estimate of the value of x corresponding to the first sign change.
Littlewood's proof is divided into two cases: the RH is assumed false (about half a page of Ingham 1932, Chapt. V), and the RH is assumed true (about a dozen pages). Stanisław Knapowski followed this up and published a paper on the number of times [math]\displaystyle{ \Delta(n) }[/math] changes sign in the interval [math]\displaystyle{ \Delta(n) }[/math].^{[2]}
Gauss's class number conjecture
This is the conjecture (first stated in article 303 of Gauss's Disquisitiones Arithmeticae) that there are only a finite number of imaginary quadratic fields with a given class number. One way to prove it would be to show that as the discriminant D → −∞ the class number h(D) → ∞.
The following sequence of theorems involving the Riemann hypothesis is described in Ireland & Rosen 1990, pp. 358–361:
Theorem (Hecke; 1918). Let D < 0 be the discriminant of an imaginary quadratic number field K. Assume the generalized Riemann hypothesis for L-functions of all imaginary quadratic Dirichlet characters. Then there is an absolute constant C such that
- [math]\displaystyle{ h(D) \gt C\frac{\sqrt{|D|}}{\log |D|}. }[/math]
Theorem (Deuring; 1933). If the RH is false then h(D) > 1 if |D| is sufficiently large.
Theorem (Mordell; 1934). If the RH is false then h(D) → ∞ as D → −∞.
Theorem (Heilbronn; 1934). If the generalized RH is false for the L-function of some imaginary quadratic Dirichlet character then h(D) → ∞ as D → −∞.
(In the work of Hecke and Heilbronn, the only L-functions that occur are those attached to imaginary quadratic characters, and it is only for those L-functions that GRH is true or GRH is false is intended; a failure of GRH for the L-function of a cubic Dirichlet character would, strictly speaking, mean GRH is false, but that was not the kind of failure of GRH that Heilbronn had in mind, so his assumption was more restricted than simply GRH is false.)
In 1935, Carl Siegel later strengthened the result without using RH or GRH in any way.
Growth of Euler's totient
In 1983 J. L. Nicolas proved (Ribenboim 1996) that
- [math]\displaystyle{ \varphi(n) \lt e^{-\gamma}\frac {n} {\log \log n} }[/math]
for infinitely many n, where φ(n) is Euler's totient function and γ is Euler's constant.
Ribenboim remarks that:
The method of proof is interesting, in that the inequality is shown first under the assumption that the Riemann hypothesis is true, secondly under the contrary assumption.
Generalizations and analogs
Dirichlet L-series and other number fields
The Riemann hypothesis can be generalized by replacing the Riemann zeta function by the formally similar, but much more general, global L-functions. In this broader setting, one expects the non-trivial zeros of the global L-functions to have real part 1/2. It is these conjectures, rather than the classical Riemann hypothesis only for the single Riemann zeta function, which account for the true importance of the Riemann hypothesis in mathematics.
The generalized Riemann hypothesis extends the Riemann hypothesis to all Dirichlet L-functions. In particular it implies the conjecture that Siegel zeros (zeros of L-functions between 1/2 and 1) do not exist.
The extended Riemann hypothesis extends the Riemann hypothesis to all Dedekind zeta functions of algebraic number fields. The extended Riemann hypothesis for abelian extension of the rationals is equivalent to the generalized Riemann hypothesis. The Riemann hypothesis can also be extended to the L-functions of Hecke characters of number fields.
The grand Riemann hypothesis extends it to all automorphic zeta functions, such as Mellin transforms of Hecke eigenforms.
Function fields and zeta functions of varieties over finite fields
(Artin 1924) introduced global zeta functions of (quadratic) function fields and conjectured an analogue of the Riemann hypothesis for them, which has been proved by Hasse in the genus 1 case and by (Weil 1948) in general. For instance, the fact that the Gauss sum, of the quadratic character of a finite field of size q (with q odd), has absolute value [math]\displaystyle{ \sqrt{q} }[/math] is actually an instance of the Riemann hypothesis in the function field setting. This led (Weil 1949) to conjecture a similar statement for all algebraic varieties; the resulting Weil conjectures were proved by Pierre Deligne (1974, 1980).
Arithmetic zeta functions of arithmetic schemes and their L-factors
Arithmetic zeta functions generalise the Riemann and Dedekind zeta functions as well as the zeta functions of varieties over finite fields to every arithmetic scheme or a scheme of finite type over integers. The arithmetic zeta function of a regular connected equidimensional arithmetic scheme of Kronecker dimension n can be factorized into the product of appropriately defined L-factors and an auxiliary factor Jean-Pierre Serre (1969–1970). Assuming a functional equation and meromorphic continuation, the generalized Riemann hypothesis for the L-factor states that its zeros inside the critical strip [math]\displaystyle{ \Re(s)\in (0,n) }[/math] lie on the central line. Correspondingly, the generalized Riemann hypothesis for the arithmetic zeta function of a regular connected equidimensional arithmetic scheme states that its zeros inside the critical strip lie on vertical lines [math]\displaystyle{ \Re(s)=1/2,3/2,\dots,n-1/2 }[/math] and its poles inside the critical strip lie on vertical lines [math]\displaystyle{ \Re(s)=1, 2, \dots,n-1 }[/math]. This is known for schemes in positive characteristic and follows from Pierre Deligne (1974, 1980), but remains entirely unknown in characteristic zero.
Selberg zeta functions
(Selberg 1956) introduced the Selberg zeta function of a Riemann surface. These are similar to the Riemann zeta function: they have a functional equation, and an infinite product similar to the Euler product but taken over closed geodesics rather than primes. The Selberg trace formula is the analogue for these functions of the explicit formulas in prime number theory. Selberg proved that the Selberg zeta functions satisfy the analogue of the Riemann hypothesis, with the imaginary parts of their zeros related to the eigenvalues of the Laplacian operator of the Riemann surface.
Ihara zeta functions
The Ihara zeta function of a finite graph is an analogue of the Selberg zeta function, which was first introduced by Yasutaka Ihara in the context of discrete subgroups of the two-by-two p-adic special linear group. A regular finite graph is a Ramanujan graph, a mathematical model of efficient communication networks, if and only if its Ihara zeta function satisfies the analogue of the Riemann hypothesis as was pointed out by T. Sunada.
Montgomery's pair correlation conjecture
(Montgomery 1973) suggested the pair correlation conjecture that the correlation functions of the (suitably normalized) zeros of the zeta function should be the same as those of the eigenvalues of a random hermitian matrix. (Odlyzko 1987) showed that this is supported by large-scale numerical calculations of these correlation functions.
Montgomery showed that (assuming the Riemann hypothesis) at least 2/3 of all zeros are simple, and a related conjecture is that all zeros of the zeta function are simple (or more generally have no non-trivial integer linear relations between their imaginary parts). Dedekind zeta functions of algebraic number fields, which generalize the Riemann zeta function, often do have multiple complex zeros (Radziejewski 2007). This is because the Dedekind zeta functions factorize as a product of powers of Artin L-functions, so zeros of Artin L-functions sometimes give rise to multiple zeros of Dedekind zeta functions. Other examples of zeta functions with multiple zeros are the L-functions of some elliptic curves: these can have multiple zeros at the real point of their critical line; the Birch-Swinnerton-Dyer conjecture predicts that the multiplicity of this zero is the rank of the elliptic curve.
Other zeta functions
There are many other examples of zeta functions with analogues of the Riemann hypothesis, some of which have been proved. Goss zeta functions of function fields have a Riemann hypothesis, proved by (Sheats 1998). The main conjecture of Iwasawa theory, proved by Barry Mazur and Andrew Wiles for cyclotomic fields, and Wiles for totally real fields, identifies the zeros of a p-adic L-function with the eigenvalues of an operator, so can be thought of as an analogue of the Hilbert–Pólya conjecture for p-adic L-functions (Wiles 2000).
Attempted proofs
Several mathematicians have addressed the Riemann hypothesis, but none of their attempts have yet been accepted as a correct solution. (Watkins 2007) lists some incorrect solutions, and more are frequently announced.
Operator theory
Hilbert and Pólya suggested that one way to derive the Riemann hypothesis would be to find a self-adjoint operator, from the existence of which the statement on the real parts of the zeros of ζ(s) would follow when one applies the criterion on real eigenvalues. Some support for this idea comes from several analogues of the Riemann zeta functions whose zeros correspond to eigenvalues of some operator: the zeros of a zeta function of a variety over a finite field correspond to eigenvalues of a Frobenius element on an étale cohomology group, the zeros of a Selberg zeta function are eigenvalues of a Laplacian operator of a Riemann surface, and the zeros of a p-adic zeta function correspond to eigenvectors of a Galois action on ideal class groups.
(Odlyzko 1987) showed that the distribution of the zeros of the Riemann zeta function shares some statistical properties with the eigenvalues of random matrices drawn from the Gaussian unitary ensemble. This gives some support to the Hilbert–Pólya conjecture.
In 1999, Michael Berry and Jonathan Keating conjectured that there is some unknown quantization [math]\displaystyle{ \hat H }[/math] of the classical Hamiltonian H = xp so that
- [math]\displaystyle{ \zeta (1/2+i\hat H) = 0 }[/math]
and even more strongly, that the Riemann zeros coincide with the spectrum of the operator [math]\displaystyle{ 1/2 + i \hat H }[/math]. This is in contrast to canonical quantization, which leads to the Heisenberg uncertainty principle [math]\displaystyle{ [x,p]=1/2 }[/math] and the natural numbers as spectrum of the quantum harmonic oscillator. The crucial point is that the Hamiltonian should be a self-adjoint operator so that the quantization would be a realization of the Hilbert–Pólya program. In a connection with this quantum mechanical problem Berry and Connes had proposed that the inverse of the potential of the Hamiltonian is connected to the half-derivative of the function
- [math]\displaystyle{ N(s)= \frac{1}{\pi}\operatorname{Arg}\xi(1/2+i\sqrt s) }[/math]
then, in Berry–Connes approach
- [math]\displaystyle{ V^{-1}(x) = \sqrt{4\pi} \frac{d^{1/2}N(x)}{dx^{1/2}} }[/math]
(Connes 1999). This yields a Hamiltonian whose eigenvalues are the square of the imaginary part of the Riemann zeros, and also that the functional determinant of this Hamiltonian operator is just the Riemann Xi function. In fact the Riemann Xi function would be proportional to the functional determinant (Hadamard product)
- [math]\displaystyle{ \det(H+1/4+s(s-1)) }[/math]
as proved by Connes and others, in this approach
- [math]\displaystyle{ \frac{\xi(s)}{\xi(0)}=\frac{\det(H+s(s-1)+1/4)}{\det(H+1/4)}. }[/math]
The analogy with the Riemann hypothesis over finite fields suggests that the Hilbert space containing eigenvectors corresponding to the zeros might be some sort of first cohomology group of the spectrum Spec (Z) of the integers. (Deninger 1998) described some of the attempts to find such a cohomology theory (Leichtnam 2005).
(Zagier 1981) constructed a natural space of invariant functions on the upper half plane that has eigenvalues under the Laplacian operator that correspond to zeros of the Riemann zeta function—and remarked that in the unlikely event that one could show the existence of a suitable positive definite inner product on this space, the Riemann hypothesis would follow. (Cartier 1982) discussed a related example, where due to a bizarre bug a computer program listed zeros of the Riemann zeta function as eigenvalues of the same Laplacian operator.
(Schumayer Hutchinson) surveyed some of the attempts to construct a suitable physical model related to the Riemann zeta function.
Lee–Yang theorem
The Lee–Yang theorem states that the zeros of certain partition functions in statistical mechanics all lie on a "critical line" with their real part equals to 0, and this has led to some speculation about a relationship with the Riemann hypothesis (Knauf 1999).
Turán's result
Pál Turán (1948) showed that if the functions
- [math]\displaystyle{ \sum_{n=1}^N n^{-s} }[/math]
have no zeros when the real part of s is greater than one then
- [math]\displaystyle{ T(x) = \sum_{n\le x}\frac{\lambda(n)}{n}\ge 0\text{ for } x \gt 0, }[/math]
where λ(n) is the Liouville function given by (−1)^{r} if n has r prime factors. He showed that this in turn would imply that the Riemann hypothesis is true. However (Haselgrove 1958) proved that T(x) is negative for infinitely many x (and also disproved the closely related Pólya conjecture), and (Borwein Ferguson) showed that the smallest such x is 72185376951205. (Spira 1968) showed by numerical calculation that the finite Dirichlet series above for N=19 has a zero with real part greater than 1. Turán also showed that a somewhat weaker assumption, the nonexistence of zeros with real part greater than 1+N^{−1/2+ε} for large N in the finite Dirichlet series above, would also imply the Riemann hypothesis, but (Montgomery 1983) showed that for all sufficiently large N these series have zeros with real part greater than 1 + (log log N)/(4 log N). Therefore, Turán's result is vacuously true and cannot be used to help prove the Riemann hypothesis.
Noncommutative geometry
Connes (1999, 2000) has described a relationship between the Riemann hypothesis and noncommutative geometry, and shows that a suitable analog of the Selberg trace formula for the action of the idèle class group on the adèle class space would imply the Riemann hypothesis. Some of these ideas are elaborated in (Lapidus 2008).
Hilbert spaces of entire functions
Louis de Branges (1992) showed that the Riemann hypothesis would follow from a positivity condition on a certain Hilbert space of entire functions. However (Conrey Li) showed that the necessary positivity conditions are not satisfied. Despite this obstacle, de Branges has continued to work on an attempted proof of the Riemann hypothesis along the same lines, but this has not been widely accepted by other mathematicians (Sarnak 2005).
Quasicrystals
The Riemann hypothesis implies that the zeros of the zeta function form a quasicrystal, meaning a distribution with discrete support whose Fourier transform also has discrete support. (Dyson 2009) suggested trying to prove the Riemann hypothesis by classifying, or at least studying, 1-dimensional quasicrystals.
Arithmetic zeta functions of models of elliptic curves over number fields
When one goes from geometric dimension one, e.g. an algebraic number field, to geometric dimension two, e.g. a regular model of an elliptic curve over a number field, the two-dimensional part of the generalized Riemann hypothesis for the arithmetic zeta function of the model deals with the poles of the zeta function. In dimension one the study of the zeta integral in Tate's thesis does not lead to new important information on the Riemann hypothesis. Contrary to this, in dimension two work of Ivan Fesenko on two-dimensional generalisation of Tate's thesis includes an integral representation of a zeta integral closely related to the zeta function. In this new situation, not possible in dimension one, the poles of the zeta function can be studied via the zeta integral and associated adele groups. Related conjecture of Fesenko (2010) on the positivity of the fourth derivative of a boundary function associated to the zeta integral essentially implies the pole part of the generalized Riemann hypothesis. Suzuki (2011) proved that the latter, together with some technical assumptions, implies Fesenko's conjecture.
Multiple zeta functions
Deligne's proof of the Riemann hypothesis over finite fields used the zeta functions of product varieties, whose zeros and poles correspond to sums of zeros and poles of the original zeta function, in order to bound the real parts of the zeros of the original zeta function. By analogy, (Kurokawa 1992) introduced multiple zeta functions whose zeros and poles correspond to sums of zeros and poles of the Riemann zeta function. To make the series converge he restricted to sums of zeros or poles all with non-negative imaginary part. So far, the known bounds on the zeros and poles of the multiple zeta functions are not strong enough to give useful estimates for the zeros of the Riemann zeta function.
Location of the zeros
Number of zeros
The functional equation combined with the argument principle implies that the number of zeros of the zeta function with imaginary part between 0 and T is given by
- [math]\displaystyle{ N(T)=\frac{1}{\pi}\mathop{\mathrm{Arg}}(\xi(s)) = \frac{1}{\pi}\mathop{\mathrm{Arg}}(\Gamma(\tfrac{s}{2})\pi^{-\frac{s}{2}}\zeta(s)s(s-1)/2) }[/math]
for s=1/2+iT, where the argument is defined by varying it continuously along the line with Im(s)=T, starting with argument 0 at ∞+iT. This is the sum of a large but well understood term
- [math]\displaystyle{ \frac{1}{\pi}\mathop{\mathrm{Arg}}(\Gamma(\tfrac{s}{2})\pi^{-s/2}s(s-1)/2) = \frac{T}{2\pi}\log\frac{T}{2\pi}-\frac{T}{2\pi} +7/8+O(1/T) }[/math]
and a small but rather mysterious term
- [math]\displaystyle{ S(T) = \frac{1}{\pi}\mathop{\mathrm{Arg}}(\zeta(1/2+iT)) =O(\log(T)). }[/math]
So the density of zeros with imaginary part near T is about log(T)/2π, and the function S describes the small deviations from this. The function S(t) jumps by 1 at each zero of the zeta function, and for t ≥ 8 it decreases monotonically between zeros with derivative close to −log t.
Karatsuba (1996) proved that every interval (T, T+H] for [math]\displaystyle{ H \ge T^{\frac{27}{82}+\varepsilon} }[/math] contains at least
- [math]\displaystyle{ H(\ln T)^{\frac{1}{3}}e^{-c\sqrt{\ln\ln T}} }[/math]
points where the function S(t) changes sign.
(Selberg 1946) showed that the average moments of even powers of S are given by
- [math]\displaystyle{ \int_0^T|S(t)|^{2k}dt = \frac{(2k)!}{k!(2\pi)^{2k}}T(\log \log T)^k + O(T(\log \log T)^{k-1/2}). }[/math]
This suggests that S(T)/(log log T)^{1/2} resembles a Gaussian random variable with mean 0 and variance 2π^{2} ((Ghosh 1983) proved this fact). In particular |S(T)| is usually somewhere around (log log T)^{1/2}, but occasionally much larger. The exact order of growth of S(T) is not known. There has been no unconditional improvement to Riemann's original bound S(T)=O(log T), though the Riemann hypothesis implies the slightly smaller bound S(T)=O(log T/log log T) (Titchmarsh 1986). The true order of magnitude may be somewhat less than this, as random functions with the same distribution as S(T) tend to have growth of order about log(T)^{1/2}. In the other direction it cannot be too small: (Selberg 1946) showed that S(T) ≠ o((log T)^{1/3}/(log log T)^{7/3}), and assuming the Riemann hypothesis Montgomery showed that S(T) ≠ o((log T)^{1/2}/(log log T)^{1/2}).
Numerical calculations confirm that S grows very slowly: |S(T)| < 1 for T < 280, |S(T)| < 2 for T < 6800000, and the largest value of |S(T)| found so far is not much larger than 3 (Odlyzko 2002).
Riemann's estimate S(T) = O(log T) implies that the gaps between zeros are bounded, and Littlewood improved this slightly, showing that the gaps between their imaginary parts tends to 0.
Theorem of Hadamard and de la Vallée-Poussin
(Hadamard 1896) and (de la Vallée-Poussin 1896) independently proved that no zeros could lie on the line Re(s) = 1. Together with the functional equation and the fact that there are no zeros with real part greater than 1, this showed that all non-trivial zeros must lie in the interior of the critical strip 0 < Re(s) < 1. This was a key step in their first proofs of the prime number theorem.
Both the original proofs that the zeta function has no zeros with real part 1 are similar, and depend on showing that if ζ(1+it) vanishes, then ζ(1+2it) is singular, which is not possible. One way of doing this is by using the inequality
- [math]\displaystyle{ |\zeta(\sigma)^3\zeta(\sigma+it)^4\zeta(\sigma+2it)|\ge 1 }[/math]
for σ > 1, t real, and looking at the limit as σ → 1. This inequality follows by taking the real part of the log of the Euler product to see that
- [math]\displaystyle{ |\zeta(\sigma+it)| = \exp\Re\sum_{p^n}\frac{p^{-n(\sigma+it)}}{n}=\exp\sum_{p^n}\frac{p^{-n\sigma}\cos(t\log p^n)}{n}, }[/math]
where the sum is over all prime powers p^{n}, so that
- [math]\displaystyle{ |\zeta(\sigma)^3\zeta(\sigma+it)^4\zeta(\sigma+2it)| = \exp\sum_{p^n}p^{-n\sigma}\frac{3+4\cos(t\log p^n)+\cos(2t\log p^n)}{n} }[/math]
which is at least 1 because all the terms in the sum are positive, due to the inequality
- [math]\displaystyle{ 3+4\cos(\theta)+\cos(2\theta) = 2 (1+\cos(\theta))^2\ge0. }[/math]
Zero-free regions
De la Vallée-Poussin (1899–1900) proved that if σ + i t is a zero of the Riemann zeta function, then 1 − σ ≥ C/log(t) for some positive constant C. In other words, zeros cannot be too close to the line σ = 1: there is a zero-free region close to this line. This zero-free region has been enlarged by several authors using methods such as Vinogradov's mean-value theorem. (Ford 2002) gave a version with explicit numerical constants: ζ(σ + i t ) ≠ 0 whenever |t | ≥ 3 and
- [math]\displaystyle{ \sigma\ge 1-\frac{1}{57.54(\log{|t|})^{2/3}(\log{\log{|t|}})^{1/3}}. }[/math]
Zeros on the critical line
(Hardy 1914) and (Hardy Littlewood) showed there are infinitely many zeros on the critical line, by considering moments of certain functions related to the zeta function. (Selberg 1942) proved that at least a (small) positive proportion of zeros lie on the line. (Levinson 1974) improved this to one-third of the zeros by relating the zeros of the zeta function to those of its derivative, and (Conrey 1989) improved this further to two-fifths.
Most zeros lie close to the critical line. More precisely, (Bohr Landau) showed that for any positive ε, all but an infinitely small proportion of zeros lie within a distance ε of the critical line. (Ivić 1985) gives several more precise versions of this result, called zero density estimates, which bound the number of zeros in regions with imaginary part at most T and real part at least 1/2+ε.
Hardy–Littlewood conjectures
In 1914 Godfrey Harold Hardy proved that [math]\displaystyle{ \zeta\left(\tfrac{1}{2}+it\right) }[/math] has infinitely many real zeros.
The next two conjectures of Hardy and John Edensor Littlewood on the distance between real zeros of [math]\displaystyle{ \zeta\left(\tfrac{1}{2}+it\right) }[/math] and on the density of zeros of [math]\displaystyle{ \zeta\left(\tfrac{1}{2}+it\right) }[/math] on the interval [math]\displaystyle{ (T,T+H] }[/math] for sufficiently large [math]\displaystyle{ T \gt 0 }[/math], and [math]\displaystyle{ H = T^{a + \varepsilon} }[/math] and with as small as possible value of [math]\displaystyle{ a \gt 0 }[/math], where [math]\displaystyle{ \varepsilon \gt 0 }[/math] is an arbitrarily small number, open two new directions in the investigation of the Riemann zeta function:
- 1. For any [math]\displaystyle{ \varepsilon \gt 0 }[/math] there exists a lower bound [math]\displaystyle{ T_0 = T_0(\varepsilon) \gt 0 }[/math] such that for [math]\displaystyle{ T \geq T_0 }[/math] and [math]\displaystyle{ H=T^{\tfrac{1}{4}+\varepsilon} }[/math] the interval [math]\displaystyle{ (T,T+H] }[/math] contains a zero of odd order of the function [math]\displaystyle{ \zeta\bigl(\tfrac{1}{2}+it\bigr) }[/math].
Let [math]\displaystyle{ N(T) }[/math] be the total number of real zeros, and [math]\displaystyle{ N_0(T) }[/math] be the total number of zeros of odd order of the function [math]\displaystyle{ ~\zeta\left(\tfrac{1}{2}+it\right)~ }[/math] lying on the interval [math]\displaystyle{ (0,T]~ }[/math].
- 2. For any [math]\displaystyle{ \varepsilon \gt 0 }[/math] there exists [math]\displaystyle{ T_0 = T_0(\varepsilon) \gt 0 }[/math] and some [math]\displaystyle{ c = c(\varepsilon) \gt 0 }[/math], such that for [math]\displaystyle{ T \geq T_0 }[/math] and [math]\displaystyle{ H=T^{\tfrac{1}{2}+\varepsilon} }[/math] the inequality [math]\displaystyle{ N_0(T+H)-N_0(T) \geq c H }[/math] is true.
Selberg's zeta function conjecture
Atle Selberg (1942) investigated the problem of Hardy–Littlewood 2 and proved that for any ε > 0 there exists such [math]\displaystyle{ T_0 = T_0(\varepsilon) \gt 0 }[/math] and c = c(ε) > 0, such that for [math]\displaystyle{ T \geq T_0 }[/math] and [math]\displaystyle{ H=T^{0.5+\varepsilon} }[/math] the inequality [math]\displaystyle{ N(T+H)-N(T) \geq cH\log T }[/math] is true. Selberg conjectured that this could be tightened to [math]\displaystyle{ H=T^{0.5} }[/math]. A. A. Karatsuba (1984a, 1984b, 1985) proved that for a fixed ε satisfying the condition 0 < ε < 0.001, a sufficiently large T and [math]\displaystyle{ H = T^{a+\varepsilon} }[/math], [math]\displaystyle{ a = \tfrac{27}{82} = \tfrac{1}{3} -\tfrac{1}{246} }[/math], the interval (T, T+H) contains at least cHln(T) real zeros of the Riemann zeta function [math]\displaystyle{ \zeta\left(\tfrac{1}{2}+it\right) }[/math] and therefore confirmed the Selberg conjecture. The estimates of Selberg and Karatsuba can not be improved in respect of the order of growth as T → ∞.
(Karatsuba 1992) proved that an analog of the Selberg conjecture holds for almost all intervals (T, T+H], [math]\displaystyle{ H = T^{\varepsilon} }[/math], where ε is an arbitrarily small fixed positive number. The Karatsuba method permits to investigate zeros of the Riemann zeta-function on "supershort" intervals of the critical line, that is, on the intervals (T, T+H], the length H of which grows slower than any, even arbitrarily small degree T. In particular, he proved that for any given numbers ε, [math]\displaystyle{ \varepsilon_1 }[/math] satisfying the conditions [math]\displaystyle{ 0\lt \varepsilon, \varepsilon_{1}\lt 1 }[/math] almost all intervals (T, T+H] for [math]\displaystyle{ H\ge\exp{\{(\ln T)^{\varepsilon}\}} }[/math] contain at least [math]\displaystyle{ H(\ln T)^{1-\varepsilon_{1}} }[/math] zeros of the function [math]\displaystyle{ \zeta\left(\tfrac{1}{2}+it\right) }[/math]. This estimate is quite close to the one that follows from the Riemann hypothesis.
Numerical calculations
The function
- [math]\displaystyle{ \pi^{-\frac{s}{2}}\Gamma(\tfrac{s}{2})\zeta(s) }[/math]
has the same zeros as the zeta function in the critical strip, and is real on the critical line because of the functional equation, so one can prove the existence of zeros exactly on the real line between two points by checking numerically that the function has opposite signs at these points. Usually one writes
- [math]\displaystyle{ \zeta(\tfrac{1}{2} +it) = Z(t)e^{-i\theta(t)} }[/math]
where Hardy's function Z and the Riemann–Siegel theta function θ are uniquely defined by this and the condition that they are smooth real functions with θ(0)=0. By finding many intervals where the function Z changes sign one can show that there are many zeros on the critical line. To verify the Riemann hypothesis up to a given imaginary part T of the zeros, one also has to check that there are no further zeros off the line in this region. This can be done by calculating the total number of zeros in the region using Turing's method and checking that it is the same as the number of zeros found on the line. This allows one to verify the Riemann hypothesis computationally up to any desired value of T (provided all the zeros of the zeta function in this region are simple and on the critical line).
Some calculations of zeros of the zeta function are listed below. So far all zeros that have been checked are on the critical line and are simple. (A multiple zero would cause problems for the zero finding algorithms, which depend on finding sign changes between zeros.) For tables of the zeros, see (Haselgrove Miller) or Odlyzko.
Year | Number of zeros | Author |
---|---|---|
1859? | 3 | B. Riemann used the Riemann–Siegel formula (unpublished, but reported in Siegel 1932). |
1903 | 15 | J. P. (Gram 1903) used Euler–Maclaurin summation and discovered Gram's law. He showed that all 10 zeros with imaginary part at most 50 range lie on the critical line with real part 1/2 by computing the sum of the inverse 10th powers of the roots he found. |
1914 | 79 (γ_{n} ≤ 200) | R. J. (Backlund 1914) introduced a better method of checking all the zeros up to that point are on the line, by studying the argument S(T) of the zeta function. |
1925 | 138 (γ_{n} ≤ 300) | J. I. (Hutchinson 1925) found the first failure of Gram's law, at the Gram point g_{126}. |
1935 | 195 | E. C. (Titchmarsh 1935) used the recently rediscovered Riemann–Siegel formula, which is much faster than Euler–Maclaurin summation. It takes about O(T^{3/2+ε}) steps to check zeros with imaginary part less than T, while the Euler–Maclaurin method takes about O(T^{2+ε}) steps. |
1936 | 1041 | E. C. (Titchmarsh 1936) and L. J. Comrie were the last to find zeros by hand. |
1953 | 1104 | A. M. (Turing 1953) found a more efficient way to check that all zeros up to some point are accounted for by the zeros on the line, by checking that Z has the correct sign at several consecutive Gram points and using the fact that S(T) has average value 0. This requires almost no extra work because the sign of Z at Gram points is already known from finding the zeros, and is still the usual method used. This was the first use of a digital computer to calculate the zeros. |
1956 | 15000 | D. H. (Lehmer 1956) discovered a few cases where the zeta function has zeros that are "only just" on the line: two zeros of the zeta function are so close together that it is unusually difficult to find a sign change between them. This is called "Lehmer's phenomenon", and first occurs at the zeros with imaginary parts 7005.063 and 7005.101, which differ by only .04 while the average gap between other zeros near this point is about 1. |
1956 | 25000 | D. H. Lehmer |
1958 | 35337 | N. A. Meller |
1966 | 250000 | R. S. Lehman |
1968 | 3500000 | (Rosser Yohe) stated Rosser's rule (described below). |
1977 | 40000000 | R. P. Brent |
1979 | 81000001 | R. P. Brent |
1982 | 200000001 | R. P. Brent, J. van de Lune, H. J. J. te Riele, D. T. Winter |
1983 | 300000001 | J. van de Lune, H. J. J. te Riele |
1986 | 1500000001 | (van de Lune te Riele) gave some statistical data about the zeros and give several graphs of Z at places where it has unusual behavior. |
1987 | A few of large (~10^{12}) height | A. M. Odlyzko (1987) computed smaller numbers of zeros of much larger height, around 10^{12}, to high precision to check Montgomery's pair correlation conjecture. |
1992 | A few of large (~10^{20}) height | A. M. Odlyzko (1992) computed a 175 million zeros of heights around 10^{20} and a few more of heights around 2×10^{20}, and gave an extensive discussion of the results. |
1998 | 10000 of large (~10^{21}) height | A. M. Odlyzko (1998) computed some zeros of height about 10^{21} |
2001 | 10000000000 | J. van de Lune (unpublished) |
2004 | ~900000000000^{[3]} | S. Wedeniwski (ZetaGrid distributed computing) |
2004 | 10000000000000 and a few of large (up to ~10^{24}) heights | X. (Gourdon 2004) and Patrick Demichel used the Odlyzko–Schönhage algorithm. They also checked two billion zeros around heights 10^{13}, 10^{14}, ..., 10^{24}. |
2020 | 12363153437138 up to height 3000175332800 | (Platt Trudgian).
They also verified the work of (Gourdon 2004) and others. |
Gram points
A Gram point is a point on the critical line 1/2 + it where the zeta function is real and non-zero. Using the expression for the zeta function on the critical line, ζ(1/2 + it) = Z(t)e^{ − iθ(t)}, where Hardy's function, Z, is real for real t, and θ is the Riemann–Siegel theta function, we see that zeta is real when sin(θ(t)) = 0. This implies that θ(t) is an integer multiple of π, which allows for the location of Gram points to be calculated fairly easily by inverting the formula for θ. They are usually numbered as g_{n} for n = 0, 1, ..., where g_{n} is the unique solution of θ(t) = nπ.
Gram observed that there was often exactly one zero of the zeta function between any two Gram points; Hutchinson called this observation Gram's law. There are several other closely related statements that are also sometimes called Gram's law: for example, (−1)^{n}Z(g_{n}) is usually positive, or Z(t) usually has opposite sign at consecutive Gram points. The imaginary parts γ_{n} of the first few zeros (in blue) and the first few Gram points g_{n} are given in the following table
g_{−1} | γ_{1} | g_{0} | γ_{2} | g_{1} | γ_{3} | g_{2} | γ_{4} | g_{3} | γ_{5} | g_{4} | γ_{6} | g_{5} | ||
0.000 | 3.436 | 9.667 | 14.135 | 17.846 | 21.022 | 23.170 | 25.011 | 27.670 | 30.425 | 31.718 | 32.935 | 35.467 | 37.586 | 38.999 |
The first failure of Gram's law occurs at the 127th zero and the Gram point g_{126}, which are in the "wrong" order.
g_{124} | γ_{126} | g_{125} | g_{126} | γ_{127} | γ_{128} | g_{127} | γ_{129} | g_{128} |
---|---|---|---|---|---|---|---|---|
279.148 | 279.229 | 280.802 | 282.455 | 282.465 | 283.211 | 284.104 | 284.836 | 285.752 |
A Gram point t is called good if the zeta function is positive at 1/2 + it. The indices of the "bad" Gram points where Z has the "wrong" sign are 126, 134, 195, 211, ... (sequence A114856 in the OEIS). A Gram block is an interval bounded by two good Gram points such that all the Gram points between them are bad. A refinement of Gram's law called Rosser's rule due to (Rosser Yohe) says that Gram blocks often have the expected number of zeros in them (the same as the number of Gram intervals), even though some of the individual Gram intervals in the block may not have exactly one zero in them. For example, the interval bounded by g_{125} and g_{127} is a Gram block containing a unique bad Gram point g_{126}, and contains the expected number 2 of zeros although neither of its two Gram intervals contains a unique zero. Rosser et al. checked that there were no exceptions to Rosser's rule in the first 3 million zeros, although there are infinitely many exceptions to Rosser's rule over the entire zeta function.
Gram's rule and Rosser's rule both say that in some sense zeros do not stray too far from their expected positions. The distance of a zero from its expected position is controlled by the function S defined above, which grows extremely slowly: its average value is of the order of (log log T)^{1/2}, which only reaches 2 for T around 10^{24}. This means that both rules hold most of the time for small T but eventually break down often. Indeed, (Trudgian 2011) showed that both Gram's law and Rosser's rule fail in a positive proportion of cases. To be specific, it is expected that in about 73% one zero is enclosed by two successive Gram points, but in 14% no zero and in 13% two zeros are in such a Gram-interval on the long run.
Arguments for and against the Riemann hypothesis
Mathematical papers about the Riemann hypothesis tend to be cautiously noncommittal about its truth. Of authors who express an opinion, most of them, such as (Riemann 1859) or (Bombieri 2000), imply that they expect (or at least hope) that it is true. The few authors who express serious doubt about it include (Ivić 2008) who lists some reasons for being skeptical, and (Littlewood 1962) who flatly states that he believes it is false, and that there is no evidence whatsoever for it and no imaginable reason that it would be true. The consensus of the survey articles (Bombieri 2000, Conrey 2003, and Sarnak 2005) is that the evidence for it is strong but not overwhelming, so that while it is probably true there is some reasonable doubt about it.
Some of the arguments for (or against) the Riemann hypothesis are listed by (Sarnak 2005), (Conrey 2003), and (Ivić 2008), and include the following reasons.
- Several analogues of the Riemann hypothesis have already been proved. The proof of the Riemann hypothesis for varieties over finite fields by (Deligne 1974) is possibly the single strongest theoretical reason in favor of the Riemann hypothesis. This provides some evidence for the more general conjecture that all zeta functions associated with automorphic forms satisfy a Riemann hypothesis, which includes the classical Riemann hypothesis as a special case. Similarly Selberg zeta functions satisfy the analogue of the Riemann hypothesis, and are in some ways similar to the Riemann zeta function, having a functional equation and an infinite product expansion analogous to the Euler product expansion. However, there are also some major differences; for example they are not given by Dirichlet series. The Riemann hypothesis for the Goss zeta function was proved by (Sheats 1998). In contrast to these positive examples, however, some Epstein zeta functions do not satisfy the Riemann hypothesis, even though they have an infinite number of zeros on the critical line (Titchmarsh 1986). These functions are quite similar to the Riemann zeta function, and have a Dirichlet series expansion and a functional equation, but the ones known to fail the Riemann hypothesis do not have an Euler product and are not directly related to automorphic representations.
- At first, the numerical verification that many zeros lie on the line seems strong evidence for it. However, analytic number theory has had many conjectures supported by large amounts of numerical evidence that turn out to be false. See Skewes number for a notorious example, where the first exception to a plausible conjecture related to the Riemann hypothesis probably occurs around 10^{316}; a counterexample to the Riemann hypothesis with imaginary part this size would be far beyond anything that can currently be computed using a direct approach. The problem is that the behavior is often influenced by very slowly increasing functions such as log log T, that tend to infinity, but do so so slowly that this cannot be detected by computation. Such functions occur in the theory of the zeta function controlling the behavior of its zeros; for example the function S(T) above has average size around (log log T)^{1/2}. As S(T) jumps by at least 2 at any counterexample to the Riemann hypothesis, one might expect any counterexamples to the Riemann hypothesis to start appearing only when S(T) becomes large. It is never much more than 3 as far as it has been calculated, but is known to be unbounded, suggesting that calculations may not have yet reached the region of typical behavior of the zeta function.
- Denjoy's probabilistic argument for the Riemann hypothesis (Edwards 1974) is based on the observation that if μ(x) is a random sequence of "1"s and "−1"s then, for every ε > 0, the partial sums
- [math]\displaystyle{ M(x) = \sum_{n \le x} \mu(n) }[/math]
- (the values of which are positions in a simple random walk) satisfy the bound
- [math]\displaystyle{ M(x) = O(x^{1/2+\varepsilon}) }[/math]
- with probability 1. The Riemann hypothesis is equivalent to this bound for the Möbius function μ and the Mertens function M derived in the same way from it. In other words, the Riemann hypothesis is in some sense equivalent to saying that μ(x) behaves like a random sequence of coin tosses. When μ(x) is non-zero its sign gives the parity of the number of prime factors of x, so informally the Riemann hypothesis says that the parity of the number of prime factors of an integer behaves randomly. Such probabilistic arguments in number theory often give the right answer, but tend to be very hard to make rigorous, and occasionally give the wrong answer for some results, such as Maier's theorem.
- The calculations in (Odlyzko 1987) show that the zeros of the zeta function behave very much like the eigenvalues of a random Hermitian matrix, suggesting that they are the eigenvalues of some self-adjoint operator, which would imply the Riemann hypothesis. However all attempts to find such an operator have failed.
- There are several theorems, such as the weak Goldbach conjecture for sufficiently large odd numbers, that were first proved using the generalized Riemann hypothesis, and later shown to be true unconditionally. This could be considered as weak evidence for the generalized Riemann hypothesis, as several of its "predictions" turned out to be true.
- Lehmer's phenomenon (Lehmer 1956) where two zeros are sometimes very close is sometimes given as a reason to disbelieve in the Riemann hypothesis. However one would expect this to happen occasionally just by chance even if the Riemann hypothesis were true, and Odlyzko's calculations suggest that nearby pairs of zeros occur just as often as predicted by Montgomery's conjecture.
- (Patterson 1988) suggests that the most compelling reason for the Riemann hypothesis for most mathematicians is the hope that primes are distributed as regularly as possible.^{[4]}
Notes
- ↑ Leonhard Euler. Variae observationes circa series infinitas. Commentarii academiae scientiarum Petropolitanae 9, 1744, pp. 160–188, Theorems 7 and 8. In Theorem 7 Euler proves the formula in the special case [math]\displaystyle{ s=1 }[/math], and in Theorem 8 he proves it more generally. In the first corollary to his Theorem 7 he notes that [math]\displaystyle{ \zeta(1)=\log\infty }[/math], and makes use of this latter result in his Theorem 19, in order to show that the sum of the inverses of the prime numbers is [math]\displaystyle{ \log\log\infty }[/math].
- ↑ Knapowski, Stanisław (1962). "On sign-changes of the difference π(x)-li(x)". Acta Arithmetica 7 (2): 107–119. doi:10.4064/aa-7-2-107-119. ISSN 0065-1036.
- ↑ Weisstein, Eric W.. "Riemann Zeta Function Zeros" (in en). https://mathworld.wolfram.com/RiemannZetaFunctionZeros.html. Retrieved 28 April 2020. "ZetaGrid is a distributed computing project attempting to calculate as many zeros as possible. It had reached 1029.9 billion zeros as of Feb. 18, 2005."
- ↑ p. 75: "One should probably add to this list the 'Platonic' reason that one expects the natural numbers to be the most perfect idea conceivable, and that this is only compatible with the primes being distributed in the most regular fashion possible..."
References
- Artin, Emil (1924), "Quadratische Körper im Gebiete der höheren Kongruenzen. II. Analytischer Teil", Mathematische Zeitschrift 19 (1): 207–246, doi:10.1007/BF01181075
- Backlund, R. J. (1914), "Sur les Zéros de la Fonction ζ(s) de Riemann", C. R. Acad. Sci. Paris 158: 1979–1981, http://gallica.bnf.fr/ark:/12148/bpt6k3111d/f1983.image
- Beurling, Arne (1955), "A closure problem related to the Riemann zeta-function", Proceedings of the National Academy of Sciences of the United States of America 41 (5): 312–314, doi:10.1073/pnas.41.5.312, PMID 16589670, Bibcode: 1955PNAS...41..312B
- Bohr, H.; Landau, E. (1914), "Ein Satz über Dirichletsche Reihen mit Anwendung auf die ζ-Funktion und die L-Funktionen", Rendiconti del Circolo Matematico di Palermo 37 (1): 269–272, doi:10.1007/BF03014823
- Bombieri, Enrico (2000), The Riemann Hypothesis – official problem description, Clay Mathematics Institute, http://www.claymath.org/sites/default/files/official_problem_description.pdf, retrieved 2008-10-25 Reprinted in (Borwein Choi).
- {{citation|isbn=978-0-387-72125-5|title=The Riemann Hypothesis: A Resource for the Afficionado and Virtuoso Alike |series=CMS Books in Mathematics|publisher=Springer|place=New York|year=2008
- Borwein, Peter; Ferguson, Ron; Mossinghoff, Michael J. (2008), "Sign changes in sums of the Liouville function", Mathematics of Computation 77 (263): 1681–1694, doi:10.1090/S0025-5718-08-02036-X, Bibcode: 2008MaCom..77.1681B
- de Branges, Louis (1992), "The convergence of Euler products", Journal of Functional Analysis 107 (1): 122–210, doi:10.1016/0022-1236(92)90103-P
- Broughan, Kevin (2017), Equivalents of the Riemann Hypothesis, Cambridge University Press, ISBN 978-1108290784
- Burton, David M. (2006), Elementary Number Theory, Tata McGraw-Hill Publishing Company Limited, ISBN 978-0-07-061607-3, https://books.google.com/books?id=XMQjuoTqqRMC
- Cartier, P. (1982), "Comment l'hypothèse de Riemann ne fut pas prouvée", Seminar on Number Theory, Paris 1980–81 (Paris, 1980/1981), Progr. Math., 22, Boston, MA: Birkhäuser Boston, pp. 35–48
- Connes, Alain (1999), "Trace formula in noncommutative geometry and the zeros of the Riemann zeta function", Selecta Mathematica. New Series 5 (1): 29–106, doi:10.1007/s000290050042
- Connes, Alain (2000), "Noncommutative geometry and the Riemann zeta function", Mathematics: frontiers and perspectives, Providence, R.I.: American Mathematical Society, pp. 35–54
- Connes, Alain (2016), "An Essay on the Riemann Hypothesis", in Nash, J. F.; Rassias, Michael, Open Problems in Mathematics, New York: Springer, pp. 225–257, doi:10.1007/978-3-319-32162-2_5
- Conrey, J. B. (1989), "More than two fifths of the zeros of the Riemann zeta function are on the critical line", J. Reine Angew. Math. 1989 (399): 1–16, doi:10.1515/crll.1989.399.1, http://www.digizeitschriften.de/resolveppn/GDZPPN002206781
- Conrey, J. Brian (2003), "The Riemann Hypothesis", Notices of the American Mathematical Society: 341–353, http://www.ams.org/notices/200303/fea-conrey-web.pdf Reprinted in (Borwein Choi).
- Conrey, J. B.; Li, Xian-Jin (2000), "A note on some positivity conditions related to zeta and L-functions", International Mathematics Research Notices 2000 (18): 929–940, doi:10.1155/S1073792800000489
- Deligne, Pierre (1974), "La conjecture de Weil. I", Publications Mathématiques de l'IHÉS 43: 273–307, doi:10.1007/BF02684373, http://www.numdam.org/item?id=PMIHES_1974__43__273_0
- Deligne, Pierre (1980), "La conjecture de Weil : II", Publications Mathématiques de l'IHÉS 52: 137–252, doi:10.1007/BF02684780, http://www.numdam.org/item?id=PMIHES_1980__52__137_0
- Deninger, Christopher (1998), "Some analogies between number theory and dynamical systems on foliated spaces", Proceedings of the International Congress of Mathematicians, Vol. I (Berlin, 1998), Documenta Mathematica, pp. 163–186, http://www.mathematik.uni-bielefeld.de/documenta/xvol-icm/00/Deninger.MAN.html
- Dudek, Adrian W. (2014-08-21), "On the Riemann hypothesis and the difference between primes", International Journal of Number Theory 11 (3): 771–778, doi:10.1142/S1793042115500426, ISSN 1793-0421, Bibcode: 2014arXiv1402.6417D
- Dyson, Freeman (2009), "Birds and frogs", Notices of the American Mathematical Society 56 (2): 212–223, http://www.ams.org/notices/200902/rtx090200212p.pdf
- Edwards, H. M. (1974), Riemann's Zeta Function, New York: Dover Publications, ISBN 978-0-486-41740-0
- Fesenko, Ivan (2010), "Analysis on arithmetic schemes. II", Journal of K-theory 5 (3): 437–557, doi:10.1017/is010004028jkt103
- Ford, Kevin (2002), "Vinogradov's integral and bounds for the Riemann zeta function", Proceedings of the London Mathematical Society, Third Series 85 (3): 565–633, doi:10.1112/S0024611502013655
- Franel, J.; Landau, E. (1924), "Les suites de Farey et le problème des nombres premiers" (Franel, 198–201); "Bemerkungen zu der vorstehenden Abhandlung von Herrn Franel (Landau, 202–206)", Göttinger Nachrichten: 198–206
- Ghosh, Amit (1983), "On the Riemann zeta function—mean value theorems and the distribution of |S(T)|", J. Number Theory 17: 93–102, doi:10.1016/0022-314X(83)90010-0
- Gourdon, Xavier (2004), The 10^{13} first zeros of the Riemann Zeta function, and zeros computation at very large height, http://numbers.computation.free.fr/Constants/Miscellaneous/zetazeros1e13-1e24.pdf
- Gram, J. P. (1903), "Note sur les zéros de la fonction ζ(s) de Riemann", Acta Mathematica 27: 289–304, doi:10.1007/BF02421310, https://zenodo.org/record/1930945/files/article.pdf
- Hadamard, Jacques (1896), "Sur la distribution des zéros de la fonction ζ(s) et ses conséquences arithmétiques", Bulletin de la Société Mathématique de France 14: 199–220, doi:10.24033/bsmf.545 Reprinted in (Borwein Choi).
- Hardy, G. H. (1914), "Sur les Zéros de la Fonction ζ(s) de Riemann", C. R. Acad. Sci. Paris 158: 1012–1014, http://gallica.bnf.fr/ark:/12148/bpt6k3111d.image.f1014.langEN Reprinted in (Borwein Choi).
- Hardy, G. H.; Littlewood, J. E. (1921), "The zeros of Riemann's zeta-function on the critical line", Math. Z. 10 (3–4): 283–317, doi:10.1007/BF01211614
- Haselgrove, C. B. (1958), "A disproof of a conjecture of Pólya", Mathematika 5 (2): 141–145, doi:10.1112/S0025579300001480, ISSN 0025-5793 Reprinted in (Borwein Choi).
- Haselgrove, C. B.; Miller, J. C. P. (1960), Tables of the Riemann zeta function, Royal Society Mathematical Tables, Vol. 6, Cambridge University Press, ISBN 978-0-521-06152-0 Review
- Hutchinson, J. I. (1925), "On the Roots of the Riemann Zeta-Function", Transactions of the American Mathematical Society 27 (1): 49–60, doi:10.2307/1989163
- Ingham, A.E. (1932), The Distribution of Prime Numbers, Cambridge Tracts in Mathematics and Mathematical Physics, 30, Cambridge University Press. Reprinted 1990, ISBN 978-0-521-39789-6, MR1074573
- Ireland, Kenneth (1990), A Classical Introduction to Modern Number Theory (Second edition), New York: Springer, ISBN 0-387-97329-X
- Ivić, A. (1985), The Riemann Zeta Function, New York: John Wiley & Sons, ISBN 978-0-471-80634-9 (Reprinted by Dover 2003)
- Ivić, Aleksandar (2008), "On some reasons for doubting the Riemann hypothesis", in Borwein, Peter; Choi, Stephen; Rooney, Brendan et al., The Riemann Hypothesis: A Resource for the Afficionado and Virtuoso Alike, CMS Books in Mathematics, New York: Springer, pp. 131–160, ISBN 978-0-387-72125-5
- Karatsuba, A. A. (1984a), "Zeros of the function ζ(s) on short intervals of the critical line" (in Russian), Izv. Akad. Nauk SSSR, Ser. Mat. 48 (3): 569–584
- Karatsuba, A. A. (1984b), "Distribution of zeros of the function ζ(1/2 + it)" (in Russian), Izv. Akad. Nauk SSSR, Ser. Mat. 48 (6): 1214–1224
- Karatsuba, A. A. (1985), "Zeros of the Riemann zeta-function on the critical line" (in Russian), Trudy Mat. Inst. Steklov. (167): 167–178
- Karatsuba, A. A. (1992), "On the number of zeros of the Riemann zeta-function lying in almost all short intervals of the critical line" (in Russian), Izv. Ross. Akad. Nauk, Ser. Mat. 56 (2): 372–397, doi:10.1070/IM1993v040n02ABEH002168, Bibcode: 1993IzMat..40..353K
- Karatsuba, A. A.; Voronin, S. M. (1992), The Riemann zeta-function, de Gruyter Expositions in Mathematics, 5, Berlin: Walter de Gruyter & Co., doi:10.1515/9783110886146, ISBN 978-3-11-013170-3
- Keating, Jonathan P.; Snaith, N. C. (2000), "Random matrix theory and ζ(1/2 + it)", Communications in Mathematical Physics 214 (1): 57–89, doi:10.1007/s002200000261, Bibcode: 2000CMaPh.214...57K
- Knauf, Andreas (1999), "Number theory, dynamical systems and statistical mechanics", Reviews in Mathematical Physics. A Journal for Both Review and Original Research Papers in the Field of Mathematical Physics 11 (8): 1027–1060, doi:10.1142/S0129055X99000325, Bibcode: 1999RvMaP..11.1027K
- von Koch, Niels Helge (1901), "Sur la distribution des nombres premiers", Acta Mathematica 24: 159–182, doi:10.1007/BF02403071
- Kurokawa, Nobushige (1992), "Multiple zeta functions: an example", Zeta functions in geometry (Tokyo, 1990), Adv. Stud. Pure Math., 21, Tokyo: Kinokuniya, pp. 219–226
- Lapidus, Michel L. (2008), In search of the Riemann zeros, Providence, R.I.: American Mathematical Society, doi:10.1090/mbk/051, ISBN 978-0-8218-4222-5
- Hazewinkel, Michiel, ed. (2001), "Zeta-function", Encyclopedia of Mathematics, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4, https://www.encyclopediaofmath.org/index.php?title=Z/z099260
- Lehmer, D. H. (1956), "Extended computation of the Riemann zeta-function", Mathematika. A Journal of Pure and Applied Mathematics 3 (2): 102–108, doi:10.1112/S0025579300001753
- "An invitation to Deninger's work on arithmetic zeta functions", Geometry, spectral theory, groups, and dynamics, Contemp. Math., 387, Providence, RI: Amer. Math. Soc., 2005, pp. 201–236, doi:10.1090/conm/387/07243.
- Levinson, N. (1974), "More than one-third of the zeros of Riemann's zeta function are on σ = 1/2", Adv. Math. 13 (4): 383–436, doi:10.1016/0001-8708(74)90074-7
- Littlewood, J. E. (1962), "The Riemann hypothesis", The scientist speculates: an anthology of partly baked idea, New York: Basic books
- van de Lune, J.; te Riele, H. J. J.; Winter, D. T. (1986), "On the zeros of the Riemann zeta function in the critical strip. IV", Mathematics of Computation 46 (174): 667–681, doi:10.2307/2008005
- Massias, J.-P.; Nicolas, Jean-Louis; Robin, G. (1988), "Évaluation asymptotique de l'ordre maximum d'un élément du groupe symétrique", Polska Akademia Nauk. Instytut Matematyczny. Acta Arithmetica 50 (3): 221–242, doi:10.4064/aa-50-3-221-242, http://matwbn.icm.edu.pl/tresc.php?wyd=6&tom=50&jez=
- Mazur, Barry; Stein, William (2015), Prime Numbers and the Riemann Hypothesis, http://wstein.org/rh/
- Montgomery, Hugh L. (1973), "The pair correlation of zeros of the zeta function", Analytic number theory, Proc. Sympos. Pure Math., XXIV, Providence, R.I.: American Mathematical Society, pp. 181–193 Reprinted in (Borwein Choi).
- Montgomery, Hugh L. (1983), "Zeros of approximations to the zeta function", in Erdős, Paul, Studies in pure mathematics. To the memory of Paul Turán, Basel, Boston, Berlin: Birkhäuser, pp. 497–506, ISBN 978-3-7643-1288-6
- Montgomery, Hugh L.; Vaughan, Robert C. (2007), Multiplicative Number Theory I. Classical Theory, Cambridge studies in advanced mathematics, 97, Cambridge University Press.ISBN 978-0-521-84903-6
- Nicely, Thomas R. (1999), "New maximal prime gaps and first occurrences", Mathematics of Computation 68 (227): 1311–1315, doi:10.1090/S0025-5718-99-01065-0, Bibcode: 1999MaCom..68.1311N, http://www.trnicely.net/gaps/gaps.html.
- Nyman, Bertil (1950), On the One-Dimensional Translation Group and Semi-Group in Certain Function Spaces, PhD Thesis, University of Uppsala: University of Uppsala
- Odlyzko, A. M.; te Riele, H. J. J. (1985), "Disproof of the Mertens conjecture", Journal für die reine und angewandte Mathematik 1985 (357): 138–160, doi:10.1515/crll.1985.357.138, http://gdz.sub.uni-goettingen.de/no_cache/dms/load/img/?IDDOC=262633
- Odlyzko, A. M. (1987), "On the distribution of spacings between zeros of the zeta function", Mathematics of Computation 48 (177): 273–308, doi:10.2307/2007890
- Odlyzko, A. M. (1990), "Bounds for discriminants and related estimates for class numbers, regulators and zeros of zeta functions: a survey of recent results", Séminaire de Théorie des Nombres de Bordeaux, Série 2 2 (1): 119–141, doi:10.5802/jtnb.22, http://www.numdam.org/item?id=JTNB_1990__2_1_119_0
- Odlyzko, A. M. (1992), The 10^{20}-th zero of the Riemann zeta function and 175 million of its neighbors, http://www.dtc.umn.edu/~odlyzko/unpublished/zeta.10to20.1992.pdf This unpublished book describes the implementation of the algorithm and discusses the results in detail.
- Odlyzko, A. M. (1998), The 10^{21}st zero of the Riemann zeta function, http://www.dtc.umn.edu/~odlyzko/unpublished/zeta.10to21.pdf
- Ono, Ken; Soundararajan, K. (1997), "Ramanujan's ternary quadratic form", Inventiones Mathematicae 130 (3): 415–454, doi:10.1007/s002220050191, Bibcode: 1997InMat.130..415O
- Patterson, S. J. (1988), An introduction to the theory of the Riemann zeta-function, Cambridge Studies in Advanced Mathematics, 14, Cambridge University Press, doi:10.1017/CBO9780511623707, ISBN 978-0-521-33535-5
- Platt, David; Trudgian, Tim (2020), The Riemann hypothesis is true up to [math]\displaystyle{ 3 \cdot 10^{12} }[/math]
- Radziejewski, Maciej (2007), "Independence of Hecke zeta functions of finite order over normal fields", Transactions of the American Mathematical Society 359 (5): 2383–2394, doi:10.1090/S0002-9947-06-04078-5, "There are infinitely many nonisomorphic algebraic number fields whose Dedekind zeta functions have infinitely many nontrivial multiple zeros."
- The New Book of Prime Number Records, New York: Springer, 1996, ISBN 0-387-94457-5
- Riemann, Bernhard (1859), "Ueber die Anzahl der Primzahlen unter einer gegebenen Grösse", Monatsberichte der Berliner Akademie, http://www.maths.tcd.ie/pub/HistMath/People/Riemann/Zeta/. In Gesammelte Werke, Teubner, Leipzig (1892), Reprinted by Dover, New York (1953). Original manuscript (with English translation). Reprinted in (Borwein Choi) and (Edwards 1974)
- Riesel, Hans; Göhl, Gunnar (1970), "Some calculations related to Riemann's prime number formula", Mathematics of Computation 24 (112): 969–983, doi:10.2307/2004630
- Riesz, M. (1916), "Sur l'hypothèse de Riemann", Acta Mathematica 40: 185–190, doi:10.1007/BF02418544
- Robin, G. (1984), "Grandes valeurs de la fonction somme des diviseurs et hypothèse de Riemann", Journal de Mathématiques Pures et Appliquées, Neuvième Série 63 (2): 187–213
- Rosser, J. Barkley; Yohe, J. M.; Schoenfeld, Lowell (1969), "Rigorous computation and the zeros of the Riemann zeta-function. (With discussion)", Information Processing 68 (Proc. IFIP Congress, Edinburgh, 1968), Vol. 1: Mathematics, Software, Amsterdam: North-Holland, pp. 70–76
- Functional Analysis, 1st edition (January 1973), New York: McGraw-Hill, 1973, ISBN 0-070-54225-2
- Salem, Raphaël (1953), "Sur une proposition équivalente à l'hypothèse de Riemann", Les Comptes rendus de l'Académie des sciences 236: 1127–1128
- Sarnak, Peter (2005), Problems of the Millennium: The Riemann Hypothesis (2004), Clay Mathematics Institute, http://www.claymath.org/sites/default/files/sarnak_rh_0.pdf, retrieved 2015-07-28 Reprinted in (Borwein Choi).
- Schoenfeld, Lowell (1976), "Sharper bounds for the Chebyshev functions θ(x) and ψ(x). II", Mathematics of Computation 30 (134): 337–360, doi:10.2307/2005976
- Schumayer, Daniel; Hutchinson, David A. W. (2011), "Physics of the Riemann Hypothesis", Reviews of Modern Physics 83 (2): 307–330, doi:10.1103/RevModPhys.83.307, Bibcode: 2011RvMP...83..307S
- "On the zeros of Riemann's zeta-function", SKR. Norske Vid. Akad. Oslo I. 10: 59 pp, 1942
- Selberg, Atle (1946), "Contributions to the theory of the Riemann zeta-function", Arch. Math. Naturvid. 48 (5): 89–155
- Selberg, Atle (1956), "Harmonic analysis and discontinuous groups in weakly symmetric Riemannian spaces with applications to Dirichlet series", J. Indian Math. Soc. (N.S.) 20: 47–87
- Serre, Jean-Pierre (1969–1970), "Facteurs locaux des fonctions zeta des varietés algébriques (définitions et conjectures)", Séminaire Delange-Pisot-Poitou 19, https://eudml.org/doc/110758
- Sheats, Jeffrey T. (1998), "The Riemann hypothesis for the Goss zeta function for F_{q}[T]", Journal of Number Theory 71 (1): 121–157, doi:10.1006/jnth.1998.2232
- Siegel, C. L. (1932), "Über Riemanns Nachlaß zur analytischen Zahlentheorie", Quellen Studien zur Geschichte der Math. Astron. Und Phys. Abt. B: Studien 2: 45–80 Reprinted in Gesammelte Abhandlungen, Vol. 1. Berlin: Springer-Verlag, 1966.
- Speiser, Andreas (1934), "Geometrisches zur Riemannschen Zetafunktion", Mathematische Annalen 110: 514–521, doi:10.1007/BF01448042, archived from the original on 2015-06-27, https://web.archive.org/web/20150627115412/http://gdz.sub.uni-goettingen.de/index.php?id=11&PPN=PPN235181684_0110&DMDID=DMDLOG_0032&L=1
- Spira, Robert (1968), "Zeros of sections of the zeta function. II", Mathematics of Computation 22 (101): 163–173, doi:10.2307/2004774
- Stein, William; Mazur, Barry (2007), What is Riemann's Hypothesis?, archived from the original on 2009-03-27, https://web.archive.org/web/20090327181331/http://modular.math.washington.edu/edu/2007/simuw07/notes/rh.pdf
- Suzuki, Masatoshi (2011), "Positivity of certain functions associated with analysis on elliptic surfaces", Journal of Number Theory 131 (10): 1770–1796, doi:10.1016/j.jnt.2011.03.007
- Titchmarsh, Edward Charles (1935), "The Zeros of the Riemann Zeta-Function", Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences (The Royal Society) 151 (873): 234–255, doi:10.1098/rspa.1935.0146, Bibcode: 1935RSPSA.151..234T
- Titchmarsh, Edward Charles (1936), "The Zeros of the Riemann Zeta-Function", Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences (The Royal Society) 157 (891): 261–263, doi:10.1098/rspa.1936.0192, Bibcode: 1936RSPSA.157..261T
- Titchmarsh, Edward Charles (1986), The theory of the Riemann zeta-function (2nd ed.), The Clarendon Press Oxford University Press, ISBN 978-0-19-853369-6
- Trudgian, Timothy (2011), "On the success and failure of Gram's Law and the Rosser Rule", Acta Arithmetica 125 (3): 225–256, doi:10.4064/aa148-3-2
- Turán, Paul (1948), "On some approximative Dirichlet-polynomials in the theory of the zeta-function of Riemann", Danske Vid. Selsk. Mat.-Fys. Medd. 24 (17): 36 Reprinted in (Borwein Choi).
- Turing, Alan M. (1953), "Some calculations of the Riemann zeta-function", Proceedings of the London Mathematical Society, Third Series 3: 99–117, doi:10.1112/plms/s3-3.1.99
- de la Vallée-Poussin, Ch.J. (1896), "Recherches analytiques sur la théorie des nombers premiers", Ann. Soc. Sci. Bruxelles 20: 183–256
- de la Vallée-Poussin, Ch.J. (1899–1900), "Sur la fonction ζ(s) de Riemann et la nombre des nombres premiers inférieurs à une limite donnée", Mem. Couronnes Acad. Sci. Belg. 59 (1) Reprinted in (Borwein Choi).
- Weil, André (1948), Sur les courbes algébriques et les variétés qui s'en déduisent, Actualités Sci. Ind., no. 1041 = Publ. Inst. Math. Univ. Strasbourg 7 (1945), Hermann et Cie., Paris
- Weil, André (1949), "Numbers of solutions of equations in finite fields", Bulletin of the American Mathematical Society 55 (5): 497–508, doi:10.1090/S0002-9904-1949-09219-4 Reprinted in Oeuvres Scientifiques/Collected Papers by Andre Weil ISBN 0-387-90330-5
- Weinberger, Peter J. (1973), "On Euclidean rings of algebraic integers", Analytic number theory ( St. Louis Univ., 1972), Proc. Sympos. Pure Math., 24, Providence, R.I.: Amer. Math. Soc., pp. 321–332
- Wiles, Andrew (2000), "Twenty years of number theory", Mathematics: frontiers and perspectives, Providence, R.I.: American Mathematical Society, pp. 329–342, ISBN 978-0-8218-2697-3
- Zagier, Don (1977), "The first 50 million prime numbers", Math. Intelligencer (Springer) 0: 7–19, doi:10.1007/BF03039306, archived from the original on 2009-03-27, https://web.archive.org/web/20090327181245/http://modular.math.washington.edu/edu/2007/simuw07/misc/zagier-the_first_50_million_prime_numbers.pdf
- Zagier, Don (1981), "Eisenstein series and the Riemann zeta function", Automorphic forms, representation theory and arithmetic (Bombay, 1979), Tata Inst. Fund. Res. Studies in Math., 10, Tata Inst. Fundamental Res., Bombay, pp. 275–301
Popular expositions
- Sabbagh, Karl (2003a), The greatest unsolved problem in mathematics, Farrar, Straus and Giroux, New York, ISBN 978-0-374-25007-2, https://archive.org/details/riemannhypothesi00sabb
- Sabbagh, Karl (2003b), Dr. Riemann's zeros, Atlantic Books, London, ISBN 978-1-843-54101-1, https://books.google.com/?id=JesSAQAAMAAJ
- du Sautoy, Marcus (2003), The music of the primes, HarperCollins Publishers, ISBN 978-0-06-621070-4, https://archive.org/details/musicofprimessea00dusa
- Rockmore, Dan (2005), Stalking the Riemann hypothesis, Pantheon Books, ISBN 978-0-375-42136-5, https://archive.org/details/stalkingriemannh00danr
- Derbyshire, John (2003), Prime Obsession, Joseph Henry Press, Washington, DC, ISBN 978-0-309-08549-6
- Watkins, Matthew (2015), Mystery of the Prime Numbers, Liberalis Books, ISBN 978-1782797814
- Frenkel, Edward (2014), The Riemann Hypothesis Numberphile, Mar 11, 2014 (video)
External links
- American institute of mathematics, Riemann hypothesis
- Zeroes database, 103 800 788 359 zeroes
- The Key to the Riemann Hypothesis - Numberphile, a YouTube video about the Riemann hypothesis by Numberphile
- Apostol, Tom, Where are the zeros of zeta of s?, http://www.math.wisc.edu/~robbin/funnysongs.html#Zeta Poem about the Riemann hypothesis, sung by John Derbyshire.
- Borwein, Peter, The Riemann Hypothesis, archived from the original on 2009-03-27, https://web.archive.org/web/20090327181245/http://oldweb.cecm.sfu.ca/~pborwein/COURSE/MATH08/LECTURE.pdf (Slides for a lecture)
- Conrad, K. (2010), Consequences of the Riemann hypothesis, https://mathoverflow.net/q/17232
- Conrey, J. Brian; Farmer, David W, Equivalences to the Riemann hypothesis, archived from the original on 2010-03-16, https://web.archive.org/web/20100316235054/http://aimath.org/pl/rhequivalences
- Gourdon, Xavier; Sebah, Pascal (2004), Computation of zeros of the Zeta function, http://numbers.computation.free.fr/Constants/Miscellaneous/zetazeroscompute.html (Reviews the GUE hypothesis, provides an extensive bibliography as well).
- Odlyzko, Andrew, Home page, http://www.dtc.umn.edu/~odlyzko/ including papers on the zeros of the zeta function and tables of the zeros of the zeta function
- Odlyzko, Andrew (2002), Zeros of the Riemann zeta function: Conjectures and computations, http://www.dtc.umn.edu/~odlyzko/talks/riemann-conjectures.pdf Slides of a talk
- Pegg, Ed (2004), Ten Trillion Zeta Zeros, Math Games website, http://www.maa.org/editorial/mathgames/mathgames_10_18_04.html. A discussion of Xavier Gourdon's calculation of the first ten trillion non-trivial zeros
- Pugh, Glen, Java applet for plotting Z(t), http://web.viu.ca/pughg/RiemannZeta/RiemannZetaLong.html
- Rubinstein, Michael, algorithm for generating the zeros, archived from the original on 2007-04-27, https://web.archive.org/web/20070427221654/http://pmmac03.math.uwaterloo.ca/~mrubinst/l_function_public/L.html.
- du Sautoy, Marcus (2006), Prime Numbers Get Hitched, Seed Magazine, http://www.seedmagazine.com/news/2006/03/prime_numbers_get_hitched.php, retrieved 2006-03-27
- Stein, William A., What is Riemann's hypothesis, archived from the original on 2009-01-04, https://web.archive.org/web/20090104104251/http://modular.math.washington.edu/edu/2007/simuw07/index.html
- de Vries, Andreas (2004), The Graph of the Riemann Zeta function ζ(s), http://math-it.org/Mathematik/Riemann/RiemannApplet.html, a simple animated Java applet.
- Watkins, Matthew R. (2007-07-18), Proposed proofs of the Riemann Hypothesis, http://secamlocal.ex.ac.uk/~mwatkins/zeta/RHproofs.htm
- Zetagrid (2002) A distributed computing project that attempted to disprove Riemann's hypothesis; closed in November 2005
Original source: https://en.wikipedia.org/wiki/ Riemann hypothesis.
Read more |