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Willie Wong
Attended Princeton University
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Willie Wong

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Did you know you could get bibtex directly from a doi? It's called DOI content negotiation and it can do a lot of other really cool tricks.

I don't know how to do get bibtex from the browser but this works on the command line:

curl -LH "Accept: application/x-bibtex" http://dx.doi.org/10.1007/s11083-012-9252-6

Here is the magic output:

@article{Dorais_2012,
doi = {10.1007/s11083-012-9252-6},
url = {http://dx.doi.org/10.1007/s11083-012-9252-6},
year = 2012,
month = {mar},
publisher = {Springer Science $\mathplus$ Business Media},
volume = {30},
number = {2},
pages = {415--426},
author = {Fran{\c{c}}ois Gilbert Dorais and Steven Gubkin and Daniel McDonald and Manuel Rivera},
title = {Automorphism Groups of Countably Categorical Linear Orders are Extremely Amenable},
journal = {Order}
}

http://www.crosscite.org/cn/
DOIs provide a persistent link to content. They identify many types of work, from journal articles to research data sets. Typically, someone interacting with DOIs will be a researcher, who will resolve DOIs found in scholarly references to content using a DOI resolver. Such researchers may not ...
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Willie Wong

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Believe it or not, it appears the TL;DR below is understated compared to what the actual reviewer report is alleged to say.
 
Authors: Hey, we are sending this paper about gender-inequalities in PhDs.

Reviewer: Your paper may be biased, please include male co-authors.
We’ve written quite a lot about the perks and pitfalls of the peer review system, but one thing we never really touched on was the risk that a reviewer might be … well, not to put too fine a point on it: a dope. But Fiona Ingleby can speak to that. Ingleby, a postdoc in …
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Willie Wong

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The last week was full of coding. (Well, the coding didn't take that much time, it was mostly full of waiting for the code to run.)

I asked a MathOverflow question sometime ago http://mathoverflow.net/questions/201680/decay-of-solutions-to-schrodinger-equation-with-local-minimum-in-potential and have not received a satisfactory answer. In the mean time I figured that I might as well write some code to see what happens. My question asked about Schrodinger equation, but I ran my code on wave, mostly because I have a wave equation solver sitting around in my drawers from a previous project.

Good news is that my expectation is not entirely wrong: the solution does have local decay as expected. The bad news is that it took quite a bit of waiting to see that! (For a deep potential I let the code run for 20+ hours to be sure that the decay is there.)

While waiting for the simulations to run, I decided to write some blog posts about the physical intuition behind the whole business. (Good thing my intuition is not too far off, else the post would've been sent straight to the bin if the simulation had shown something else.)
If you have not seen my previous two posts, you should read them first. Shooting a classical particle ...and scattering a quantum particle In the two previous posts, I shot particles (okay, simulat...
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Regarding a crazy (not being hyperbolic here) proposal put forward in the Iowa legislature.
Apparently, Iowa's politicians intend to enrich the tenure experience by annual gladiatorial games at state schools, regardless of tenure: those being evaluated below some threshold shall be
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Lucky they still have such a thing as tenure in the US system, unlike some other countries...
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Yes, he is that Rubik.
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According to the internet, 2913892 is not a plausible score for this board configuration, at least not in the Cirulli version:

http://www.reddit.com/r/2048/comments/214njx/highest_possible_score_for_2048_warning_math

(The screenshot is of a modified version, because it allows undo.)
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Willie Wong

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So researchers found that a lot of free apps on the Android store connect to Ad servers and tracking servers. So far it is "nothing to see here". What's interesting is that the researchers use this paper also to advertise their upcoming App which will make transparent to the users exactly what sort of network traffic is used by the installed apps, and they are rather unabashed about:

"We use SandroProxyLib to establish a local HTTP (and HTTPS) proxy. By installing its own certificates, the proxy is able to emulate a man-in-the-middle for SSL traffic, which it can then monitor."

As far as I can tell, the proposed App is not released as OpenSource, and the authors are just releasing an installable package file for Android. Forgive me for not wanting to voluntarily allow a MITM attack on my phone from a non-vetted source!
Abstract: There are over 1.2 million applications on the Google Play store today with a large number of competing applications for any given use or function. This creates challenges for users in selecting the right application. Moreover, some of the applications being of dubious origin, ...
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So the telecom company Orange (in Switzerland) has changed its name to Salt. With big fanfare and what not.

They had been texting us every few days the last few weeks "anticipating" this big name change. And today I found out that the change consists (for end users) essentially of:

* Breaking our online log-ins; we have to re-register a new account on the new website
* Completely breaking the mobile App that one uses to manage subscriptions and plan add-ons. New app "will be available soon".

So, they killed the old brand recognition. Replacing one generic word (orange) with an arguably even more generic word (salt). And resulting in building a new website, rebranding the physical stores, breaking and re-engineering a whole load of peripheral infrastructure, and zero upgrades to the phone service as far as I can see. It amazes me that sinking all this money came across as a good idea in running a company.
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On the misuse of bibliometrics: the Leiden manifesto

"As scientometricians, social scientists and research administrators, we have watched with increasing alarm the pervasive misapplication of indicators to the evaluation of scientific performance. The following are just a few of numerous examples. Across the world, universities have become obsessed with their position in global rankings (such as the Shanghai Ranking and Times Higher Education's list), even when such lists are based on what are, in our view, inaccurate data and arbitrary indicators."

"Some recruiters request h-index values for candidates. Several universities base promotion decisions on threshold h-index values and on the number of articles in 'high-impact' journals. Researchers' CVs have become opportunities to boast about these scores, notably in biomedicine. Everywhere, supervisors ask PhD students to publish in high-impact journals and acquire external funding before they are ready."

So the following principles are put forward:

1) Quantitative evaluation should support qualitative, expert assessment.

2) Measure performance against the research missions of the institution, group or researcher.

3) Protect excellence in locally relevant research.

4) Keep data collection and analytical processes open, transparent and simple.

5) Allow those evaluated to verify data and analysis.

6) Account for variation by field in publication and citation practices.

7) Base assessment of individual researchers on a qualitative judgement of their portfolio.

8) Avoid misplaced concreteness and false precision.

9) Recognize the systemic effects of assessment and indicators.

10) Scrutinize indicators regularly and update them.
Use these ten principles to guide research evaluation, urge Diana Hicks, Paul Wouters and colleagues.
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You probably have to be either a mathematical/theoretical physicist, or a friend thereof, to truly appreciate this one. (As the URL suggests, there's more than one of these things.)
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Social political aspect of the article aside, near the bottom there is the claim that the three conditions

1. Progressive tax rate
2. Tax paid for a couple independent of how the income is split between the two couple
3. Tax paid independent of whether a couple is married

cannot be all satisfied together.

The way it is phrased is a bit confusing. But under the hood, this is a very simple mathematics exercise in convex analysis. To see this it is easier to actually generalize and re-write 1 to

1'. Tax paid scales non-linearly with income.

And here we see the impossibility really clearly. 3 stipulates that taxes paid is independent of other factors such as marriage, so we can write the function T(I) for taxes paid based on income. 2 tells us that T(I) must be linear. And tax rate, being the derivative T'(I), must be constant, which is then incompatible with 1'.

Now let dig deeper. Let us compare two schemes:

a. Drop condition 3. Replace it by saying that married couples pay an amount of tax equivalent to two single people earning the average of the their incomes. (This satisfies condition 2)
b. Drop condition 2. Period, and keep condition 3.

In scheme (a) with a progressive tax regime (where the taxation rate increases with income and so taxes is a convex function of income), we see that this would not penalize marriage. Indeed, for a couple with roughly equal incomes this scheme makes almost no changes. For couples with disparate incomes, this scheme lowers the effective tax rate.

In scheme (b) with a progressive tax regime, we see that couples with one giant earner is worse off than couples with roughly equal incomes.

Now comparing the naive scheme (a) to what is actually reported in the NY Times article, it appears that

The US government wrote its tax code to deliberately penalize married couples with similar income levels.

or, to put it in a slightly inflammatory and irresponsible way,

Uncle Sam's tax code is deliberately against gender (pay) equality.
 
Really nice visualization of the marriage penalty/bonus from the NYT! It would be interesting to learn whether this affects the timing of weddings, especially around the new year. It looks to me like most two-earner software engineer couples would be in penalty territory.
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Yes. The history is that they went from scheme (b) to scheme (a), but single people complained that they were being penalized. So they tweaked scheme (a) by adding the marriage penalty to make things more fair to single people.
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Via +David Jao

I have been pronouncing Huygens wrong, at least by Dutch standards. But I wonder if any non Dutch mathematicians will understand the correct version. 
How to pronounce "Huygens". In the physics community we have our heros, about whom we collect quotations, legends, and so on. But we often don't know much about the history of these giants, or even the pronunciation of their names. A case in point is the Dutch physicist Christiaan Huygens, ...
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All algebraic geometers are familiar with the work of Looijenga; far fewer know who this "Loyenkha" fellow you keep mentioning is.
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6accdæ13eff7i319n4o4qrr4s9t12vx... at least, it pays the bills.
Introduction
Mostly I identify as a mathematician. My specialties are partial differential equations (especially nonlinear hyperbolic systems), geometric analysis, and mathematical physics (especially general relativity). You can find me somewhat active on MathOverflow.

I am an apprentice computer ninja. My computers usually run some flavour of Linux or Unix, I know my way around LaTeX quite well, and I am known to do a bit of scripting (I used to be a "clobber things together in bash" sort of guy, but now I prefer Python). I do the vast majority of my text editing in Vim, and prefer Mutt as my e-mail client.

I aspire to be a polyglot. Right now I speak English, French, and Chinese. I hope to add Japanese and Greek to that list.
Education
  • Princeton University
    Mathematics (PhD), 2005 - 2009
  • Princeton University
    Mathematics (AB), 2001 - 2005