Here’s a nice idea: a journal for people to write about open problems, with the aim of inspiring someone to have a go at solving them. *Open Problems in Mathematics* is a new open-access journal set up by Krzysztof Burdzy and a few others, and it’s online now.

# You're reading: Phil. Trans. Aperiodic.

### Proof News: Designs exist!

The year in proofs has started with a big result in combinatorics: the existence conjecture for designs. As usual, weightier minds than ours have comprehensively explained the result, so I’ll just give a brief summary of the problem and then some links.

### “Bounded gaps between primes” by Yitang Zhang now available

To complete the story started as a rumour report in ‘Primes gotta stick together‘ and confirmed in ‘Primes really do stick together‘, here we report that *Annals of Mathematics* has posted the PDF of ‘Bounded gaps between primes‘ by Yitang Zhang on its ‘to appear in forthcoming issues’ page. After the seminar on 13th May, Zhang apparently submitted a revised manuscript on 16 May, which was accepted 21 May 2013. So if you’ve been itching for details, here’s your chance (assuming you have access to a subscription to *Annals*).

Here’s the abstract:

It is proved that \[ \liminf_{n\to \infty}\, (p_{n+1} – p_n) < 7 \times 10^7 \text{,}\] where $p_n$ is the $n$-th prime.

Our method is a refinement of the recent work of Goldston, Pintz and Yildirim on the small gaps between consecutive primes. A major ingredient of the proof is a stronger version of the Bombieri-Vinogradov theorem that is applicable when the moduli are free from large prime divisors only (see Theorem 2), but it is adequate for our purpose.

**The paper: ***Bounded gaps between primes* by Yitang Zhang, in *Annals of Mathematics*.

### First papers in Forum of Mathematics Pi and Sigma

I had hoped that The Future of Scholarly Mathematical Intercourse would arrive chaperoned by The Future of Publishing.

The first papers in Cambridge University Press’s new journals, Forum of Mathematics Pi and Forum of Mathematics Sigma, have been published — *$p$-adic Hodge theory for rigid-analytic varieties* by Peter Scholze in FoM Pi, and *Generic mixing theory via vanishing Hodge models* by Minhea Popa and Christian Schnell in FoM Sigma. But since the journals are more interesting for the medium they’re delivered by than their message, I’d like to take a look at the experience I had when accessing them.

### All odd integers greater than 7 are the sum of three odd primes!

It seems that big mathematical advances are like buses – you wait ages for one, and then two come along at once. Also revealed yesterday was a proof of the odd Goldbach conjecture: that all odd numbers greater than 7 can be written as the sum of exactly three odd primes. The proof is contained in Major arcs for Goldbach’s theorem, a paper submitted to the arXiv by Harald Helfgott, who’s a mathematician at the École Normale Supérieure in Paris. This new paper completes the work started in Helfgott’s previous paper, Minor arcs for Golbach’s problem, published last year.

The strong Goldbach conjecture states that every *even* number can be written as the sum of *two* primes. This is still unproven, and remains one of the long-standing unproven results in number theory. Sadly, it’s the opinion of Terence Tao, among others, that the method used to prove the weak conjecture probably won’t work on the strong conjecture.

**The paper:** Major arcs for Goldbach’s theorem by Harald Helfgott

*via Terry Tao on Google+*

### Primes gotta stick together

**Update 14/05/2013: **The seminar was successful: Zhang announced that his proof has already been refereed for the *Annals*, and everyone seems happy with it.

Hard Maths news now: there’s a rumour going round that Yitang (Tom) Zhang of the University of New Hampshire reckons he can prove that there are infinitely many different pairs of primes at most 70,000,000 apart.

### Crimewaves really are waves – but they can be stopped

Nothing puts your home insurance premium up like having been burgled in the past – because it means you’re more likely to be burgled again. Stanford researcher Nancy Rodríguez, with colleagues Henri Berestycki (who is first author, for the record) and Lenya Ryzhik, has developed a travelling waves model to explain this phenomenon – and, more importantly, how to stop it.

Crime, according to past research, tends to cluster in particular neighbourhoods – and even individual houses. Once a crime epicentre has been established, criminal activity tends to spread out in a wave pattern, gradually engulfing larger and larger areas.