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Blog Profile / Terence Tao's Blog


URL :http://terrytao.wordpress.com/
Filed Under:Academics / Mathematics
Posts on Regator:496
Posts / Week:1.5
Archived Since:December 12, 2008

Blog Post Archive

254A, Supplement 6: A cheap version of the theorems of Halasz and Matomaki-Radziwill (optional)

In analytic number theory, it is a well-known phenomenon that for many arithmetic functions of interest in number theory, it is significantly easier to estimate logarithmic sums such as than it is to estimate summatory functions such as (Here we are normalising to be roughly constant in size, e.g. as.) For instance, when is […]

254A, Notes 7: Linnik’s theorem on primes in arithmetic progressions

In the previous set of notes, we saw how zero-density theorems for the Riemann zeta function, when combined with the zero-free region of Vinogradov and Korobov, could be used to obtain prime number theorems in short intervals. It turns out that a more sophisticated version of this type of argument also works to obtain prime […]

254A, Notes 6: Large values of Dirichlet polynomials, zero density estimates, and primes in short intervals

In the previous set of notes, we studied upper bounds on sums such as for that were valid for all in a given range, such as ; this led in turn to upper bounds on the Riemann zeta for in the same range, and for various choices of. While some improvement over the trivial […]

254A, Notes 5: Bounding exponential sums and the zeta function

We return to the study of the Riemann zeta function, focusing now on the task of upper bounding the size of this function within the critical strip; as seen in Exercise 43 of Notes 2, such upper bounds can lead to zero-free regions for, which in turn lead to improved estimates for the […]

254A, Supplement 5: The linear sieve and Chen’s theorem (optional)

We continue the discussion of sieve theory from Notes 4, but now specialise to the case of the linear sieve in which the sieve dimension is equal to, which is one of the best understood sieving situations, and one of the rare cases in which the precise limits of the sieve method are known. […]

254A, Notes 4: Some sieve theory

Many problems in non-multiplicative prime number theory can be recast as sieving problems. Consider for instance the problem of counting the number of pairs of twin primes contained in for some large ; note that the claim that for arbitrarily large is equivalent to the twin prime conjecture. One can obtain this count by any […]

254A, Notes 3: The large sieve and the Bombieri-Vinogradov theorem

A fundamental and recurring problem in analytic number theory is to demonstrate the presence of cancellation in an oscillating sum, a typical example of which might be a correlation between two arithmetic functions and, which to avoid technicalities we will assume to be finitely supported (or that the variable is localised to a finite […]

254A, Supplement 4: Probabilistic models and heuristics for the primes (optional)

We now move away from the world of multiplicative prime number theory covered in Notes 1 and Notes 2, and enter the wider, and complementary, world of non-multiplicative prime number theory, in which one studies statistics related to non-multiplicative patterns, such as twins. This creates a major jump in difficulty; for instance, even the […]

The Erdos-Ulam problem, varieties of general type, and the Bombieri-Lang conjecture

In 1946, Ulam, in response to a theorem of Anning and Erdös, posed the following problem: Problem 1 (Erdös-Ulam problem) Let be a set such that the distance between any two points in is rational. Is it true that cannot be (topologically) dense in ? The paper of Anning and Erdös addressed the case that […]

Long gaps between primes

Kevin Ford, Ben Green, Sergei Konyagin, James Maynard, and I have just uploaded to the arXiv our paper “Long gaps between primes“. This is a followup work to our two previous papers (discussed in this previous post), in which we had simultaneously shown that the maximal gap between primes up to exhibited a lower bound […]

254A, Supplement 3: The Gamma function and the functional equation (optional)

In Notes 2, the Riemann zeta function (and more generally, the Dirichlet -functions ) were extended meromorphically into the region in and to the right of the critical strip. This is a sufficient amount of meromorphic continuation for many applications in analytic number theory, such as establishing the prime number theorem and its variants. The […]

254A, Notes 2: Complex-analytic multiplicative number theory

In Notes 1, we approached multiplicative number theory (the study of multiplicative functions and their relatives) via elementary methods, in which attention was primarily focused on obtaining asymptotic control on summatory functions and logarithmic sums. Now we turn to the complex approach to multiplicative number theory, in which the focus is instead on obtaining […]

254A, Supplement 2: A little bit of complex and Fourier analysis

We will shortly turn to the complex-analytic approach to multiplicative number theory, which relies on the basic properties of complex analytic functions. In this supplement to the main notes, we quickly review the portions of complex analysis that we will be using in this course. We will not attempt a comprehensive review of this subject; […]

Random matrices have simple spectrum

Van Vu and I have just uploaded to the arXiv our paper “Random matrices have simple eigenvalues“. Recall that an Hermitian matrix is said to have simple eigenvalues if all of its eigenvalues are distinct. This is a very typical property of matrices to have: for instance, as discussed in this previous post, in the […]

254A, Supplement 1: A little bit of algebraic number theory (optional)

Analytic number theory is only one of many different approaches to number theory. Another important branch of the subject is algebraic number theory, which studies algebraic structures (e.g. groups, rings, and fields) of number-theoretic interest. With this perspective, the classical field of rationals, and the classical ring of integers, are placed inside the […]

245A, Supplement 1: A little bit of algebraic number theory (optional)

Analytic number theory is only one of many different approaches to number theory. Another important branch of the subject is algebraic number theory, which studies algebraic structures (e.g. groups, rings, and fields) of number-theoretic interest. With this perspective, the classical field of rationals, and the classical ring of integers, are placed inside the […]

254A, Notes 1: Elementary multiplicative number theory

In analytic number theory, an arithmetic function is simply a function from the natural numbers to the real or complex numbers. (One occasionally also considers arithmetic functions taking values in more general rings than or, as in this previous blog post, but we will restrict attention here to the classical situation of real or […]

A general parity problem obstruction

Many problems and results in analytic prime number theory can be formulated in the following general form: given a collection of (affine-)linear forms, none of which is a multiple of any other, find a number such that a certain property of the linear forms are true. For instance: For the twin prime conjecture, one […]

254A announcement: Analytic prime number theory

In the winter quarter (starting January 5) I will be teaching a graduate topics course entitled “An introduction to analytic prime number theory“. As the name suggests, this is a course covering many of the analytic number theory techniques used to study the distribution of the prime numbers. I will list the topics I […]

Discretised wave equations

The wave equation is usually expressed in the form where is a function of both time and space, with being the Laplacian operator. One can generalise this equation in a number of ways, for instance by replacing the spatial domain with some other manifold and replacing the Laplacian with the Laplace-Beltrami operator or adding […]

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