Andrew Granville's Home Page

2016 Publications

Gaps between fractional parts, and additive combinatorics
(with Antal Balog and Jozsef Solymosi) Quarterly Journal of Mathematics, (2015 or 16), 1-11.

We give bounds on the number of distinct differences \( N_a-a\) as \( a\) varies over all elements of a given finite set \( A \subset (\mathbb R/\mathbb Z)^d,\ d\geq 1\) and \( Na\) is a nearest neighbour to \( a\) .

Article and Journal Link

Mean values of multiplicative functions over function fields
(with Adam Harper and K. Soundararajan)
Research in Number Theory. (e-pub December 2015), 1-25.

We discuss the mean values of multiplicative functions over function fields. In particular, we adapt the authors' new proof of Halasz's theorem on mean values to this simpler setting. Several of the technical difficulties that arise over the integers disappear in the function field setting, which helps bring out more clearly the main ideas of the proofs over number fields. We also obtain Lipschitz estimates showing the slow variation of mean values of multiplicative functions over function fields, which display some features that are not present in the integer situation.

Article and (open access) Journal Link

Big biases amongst products of two primes
(with David Dummit and Hershy Kisilevsky)
Mathematika 62 (2016) 502-507

David Dummit and Hershy Kisilevsky observed from calculation that the Legendre symbols \( (p/q)\) and \( (q/p)\) are unequal for rather more than a quarter of the pairs of odd primes \( p \) and \( q\) with \( pq\leq x\) , during some calculations. In fact almost \( 30 \% \) of the \( pq\)'s up to a million satisfy \( p\equiv q\equiv 3 \pmod 4\) . Together we found that this is no accident and that the bias up to \( x\) is roughly \( 1 +1/3(\log\log x-1)\) . This is a much stronger bias than the traditional "prime race" problem. When doing the math one finds that this problems about \( pq\) 's is equivalent to the prime race problem, for primes \( \equiv 3 \pmod 4\) versus those \( \equiv 1 \pmod 4\), in which we weight each prime by its reciprocal.

Article and Journal

Sum-Product formulae
(with Joszef Solymosi)
Recent Trends in Combinatorics, IMA, Springer, 159 (2016) 419-451

Here we survey the latest developments about sum-product estimates, especially over finite fields

Article and Journal