# Category Archives: mathematics: people

## Maryam Mirzakhani makes history

The IMU has just announced this year’s Fields medal winners. For the first time ever, a Fields medal has been awarded to a woman, Maryam Mirzakhani. I will have the honour of attending the ceremony this morning.

The official press release on Mirzakhani’s research is available, as are the citations for the other Fields medalists. I’d like to speak to what the selection of a female Fields medalist means to me as a woman and a mathematician. In that, I would like to paraphrase something that Melissa Harris-Perry has said about the election of President Obama. Mirzakhani’s selection does exactly nothing to convince me that women are capable of doing mathematical research at the same level as men. I have never had any doubt about that in the first place, and I have said so here many times. What I take from it instead is that we as a society, men and women alike, are becoming better at encouraging and nurturing mathematical talent in women, and more capable of recognizing excellence in women’s work. I’ve said here before that the highest level of achievement within the age limit set for the Fields medals requires a confluence of both exceptional talent and favourable circumstances. Talent must be recognized, nourished, directed in productive ways, accomplishment must be acknowledged and promoted. Among the setbacks I experience every day and hear about from other women, Mirzakhani’s award offers a reason for guarded optimism, a point of evidence that sufficient dents have been made in the many layers of glass ceilings that a woman could break through all of them to the highest level.

Filed under mathematics: people, women in math

## Szemeredi wins the Abel Prize

Congratulations to Endre Szemerédi on winning this year’s Abel Prize in mathematics! Ever since my work took a turn towards combinatorics years ago, I have been constantly awed by the breadth, depth and vision in Szemerédi’s work. His impact on mathematics has been beyond profound, not just in combinatorics, but also in many adjacent fields, from harmonic analysis and number theory to computer science. I am especially happy to see his name alongside those of the previous prize winners, such as Serre, Atiyah and Singer, Carleson, Lax, Gromov, or Milnor. He has long deserved this level of recognition.

Tim Gowers, who spoke on Szemerédi’s work following today’s announcement, has posted a written version of his presentation here.

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Congratulations to Karsten Chipeniuk, who has just graduated with a Ph.D. degree. Karsten will be starting a postdoc job at Indiana University later this summer.

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## A public service announcement

We interrupt regular programming to congratulate Matt Bond on winning the NSF postdoctoral fellowship to work with me at UBC. Matt is coming here for 3 years starting this summer.

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## Various and sundry

In no particular order:

♦ The Harmonic Analysis group at UBC has a new website. We’re still adding content and working out the kinks, but that’s basically what it’s going to look like. The website was created by Tom Hollai and Krista Pravetz of eMarketing Vancouver. We’ve enjoyed working with them and would recommend them to anyone needing to upgrade their web presence.

♦ The Erwin Schrödinger Institute, recently threatened with extinction, has been granted a reprieve:

The ESI will continue operation in its present form until May 31, 2011. Thereafter it will form a ‘Research Platform’ of the University of Vienna with the (unchanged) name ‘Erwin Schrödinger Institute for Mathematical Physics’.

Funding of the ESI research programmes and workshops in 2011 and 2012 seems assured. Unfortunately the Junior Research Programme of the ESI has to be suspended until further notice due to lack of financial support. This suspension does not affect current Junior Research Fellowships.

The Directors of the ESI would like to take this opportunity to express their gratitude to the scientific community for their overwhelming support of the ESI during these difficult negotiations.

♦ NSERC long range plan: I ended up not attending the information session at the CMS meeting. I’d been planning to go, but then other activities got in the way. Turns out, if you invite 20+ people from all over the continent to come and speak in your session, it’s hard to tell them once they’re here that you won’t hang out with them because you have a policy meeting to catch – and an information session at that, as opposed to a committee meeting where decisions are actually made.

It’s not clear how much I really missed, though. The steering committee has posted the slides from the presentation along with some FAQ answers. Compared to the expanded terms of reference, there’s some additional information about the procedure but (as far as I can tell) not about the substance of what they’re doing. All the substantive information is phrased in frustratingly general terms, for instance “How is research in mathematics and statistics impacting science.” Really? Where do we even start?

The FAQ answers look like so:

“Why isn’t there representation from ______ on the steering committee?”

• It was important to keep the committee small enough to function effectively, and there are many different aspects to try to balance. Everyone on the committee wears several hats!

• Because the committee is limited in size, it is very important that we get input from ________, ideally in the form of discussion papers, but comments to the committee via the website are also welcome.

While I’m sitting here and waiting for someone to ask me for a discussion paper, I’ve spent some time browsing the committee website, and (in case any committee members are reading this) I’d like to suggest a few improvements to its interactive functionality. Right now, the page setup does not encourage discussion of any of the specific issues on the agenda. The only places where comments can be posted are the three lonely blog entries (look under “recent posts”), so that if I wanted for example to submit feedback on the mathematics institutes – which I do – I’d have to post it under some completely unrelated article where no one would know to look for it. Now, I happen to have a reasonably popular (by math standards) blog where I can post whatever I like and there is a good chance that people will see it. But in terms of engaging the community, having designated comment threads for specific topics on the committee website would work much better.

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Filed under mathematics: people, research funding

## The men who stare at formulas

The n-category Café has a post about “Dangerous Knowledge”, the BBC documentary I reviewed here some time ago; there’s also a discussion in the comments on whether mathematicians (or academics, or creative types) are really different from “normal” people. If you came here from the link over there, welcome, and here’s hoping that you’ll enjoy this recent interview with John Nash. (Hat tip to 3QD.)

Around the 6-minute mark in the second video, Nash is asked explicitly whether his mental illness might have in some way contributed to his creativity and enabled his mathematical work. He points out in response that his work in game theory was all done before the onset of his mental problems and that he “did not develop any ideas, particularly on game theory, while being mentally irrational”. He also recalls a mistake in a published paper that he completed shortly before the breakdown and suggests that it may have been due to a malfunction of his mind.

Filed under mathematics: people, movies

## The Piatetski-Shapiro theorem

I have just learned that Ilya Piatetski-Shapiro died on February 21, 2009, just a month short of his 80th birthday. Most of his research has been in algebraic number theory and representation theory. I’m not a number theorist, and I know even less about representation theory, so I can’t tell you much about his work in those areas. However, I would like to tell you about an early result of his on the summability of Fourier series, known as the Piatetski-Shapiro theorem in harmonic analysis.

Suppose that $c_k,\ k\in{\mathbb Z}$, is a sequence with the property that $\sum_{k=-\infty}^\infty c_ke^{2\pi i kx}=0$ almost everywhere on $[0,1]$. Does it follow that $c_k=0$ for all $k$? It turns out (due to Menshov) that the answer is negative. Hence the following definition.

A set $E\subset [0,1]$ is called a set of uniqueness if the only sequence $c_k$ such that $\sum_{k=-\infty}^\infty c_ke^{2\pi i kx}=0$ for all $x\in [0,1]\setminus E$ is $c_k=0$ for all $k$. Otherwise, $E$ is called a set of multiplicity.

If $E$ is closed, it is known that $E$ is a set of multiplicity if and only if it supports a distribution whose Fourier coefficients tend to 0 at infinity.

It was thought for a while that the word “distribution” in the last sentence can be replaced by “measure”. This is what Piatetski-Shapiro disproved.

Theorem (Piatetski-Shapiro). There is a closed set $E\subset[0,1]$ such that $E$ is a set of multiplicity, but does not support any measure $\mu$ with $\widehat{\mu}(k)\to 0$ as $|k|\to\infty$.

In other words, $E$ supports a distribution whose Fourier coefficients vanish at infinity, but does not support a measure with the same property!

Piatetski-Shapiro proved that one can take $E$ to be the set of all numbers in $[0,1]$ whose dyadic expansion $\sum_{j=1}^\infty r_j2^{-j}$ obeys $n^{-1}\sum_{j=1}^n r_j\leq r$, where $r$ is a fixed number in $(0,1/2)$.

Alternative proofs of the Piatetski-Shapiro theorem were given by Kaufman, Körner and others. The following brief sketch of the Kaufman-Körner argument is based on an exposition by Nir Lev. See the introduction to his thesis for the full length version.

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Filed under mathematics: people, mathematics: research