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Posts

September 01, 2015

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2:45 PM | John Baldwin on Model Theory and the Philosophy of Mathematical Practice
John T. Baldwin (Illinois-Chicago) has posted a draft of his book Formalism without Foundationalism: Model Theory and the Philosophy of Mathematical Practice and is inviting comments. On, FOM he wrote: Martin Davis posted a couple of days ago a message containing this sentence. “Gödel showed us that the wild infinite could not really be separated from…
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1:11 PM | The Princeton Companion to Applied Mathematics
The Princeton Companion to Applied Mathematics just appeared: It includes an introductory article on kinetic theory I wrote together with Cédric Villani, and many other interesting papers.Filed under: mathematical post Tagged: Boltzmann equation, kinetic theory
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12:30 PM | 9/1/15
√9 + 1 + 1 = 5
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12:52 AM | KIAS-Kalender September 2015
(Zum Vergrößern auf das Bild klicken.) 1 ist der natürliche Logarithmus der eulerschen Zahl e und weil der natürliche Logarithmus auch die Stammfunktion von ist, ergibt sich daraus . Bei der 2 geht es um die Goldbach-Vermutung, d.h. die Frage, ob es unendlich viele Primzahlzwillinge gibt. Die 3 kann man als erste (oder besser nullte)…

August 31, 2015

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10:24 PM | van Ekeren, Möller, Scheithauer on holomorphic orbifolds
There aren’t many blog posts about vertex operator algebras, so I thought I’d help fill this gap by mentioning a substantial advance by Jethro van Ekeren, Sven Möller, and Nils Scheithauer that appeared on the ArXiv last month. The most important feature is that this paper resolves several folklore conjectures that have been around since […]
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10:15 PM | likelihood-free inference in high-dimensional models
“…for a general linear model (GLM), a single linear function is a sufficient statistic for each associated parameter…” The recently arXived paper “Likelihood-free inference in high-dimensional models“, by Kousathanas et al. (July 2015), proposes an ABC resolution of the dimensionality curse [when the dimension of the parameter and of the corresponding summary statistics] by turning […]
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7:54 PM | Plans Are Worthless, But…
I first heard about semester planning when I began my postdoc at the University of the Pacific. I couldn’t even parse the phrase then: one made plans for things that one had some control over, like a vacation, or to … Continue reading →
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5:33 PM | Wrangling generators for subobjects
Describes a new categorical definition of the degree of generation of a subobject.
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4:29 PM | September
I already posted part of this picture, a signpost on the edge of the Olympic Park back in 2011. I tagged it with the last phrase of the second verse of Procol Harum’s apocalyptic song Homburg: “The signposts cease to … Continue reading →
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4:28 PM | How Joe Traub Beat the Street
An insight into the computation of financial information Columbia memorial source Joseph Traub passed away just a week ago, on August 24th. He is best known for his computer science leadership positions at CMU, Columbia, CSTB, the Journal of Complexity—they all start with “C.” CSTB is the Computer Science and Telecommunications Board of the National […]
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3:58 PM | The enigma of Robert Hooke
In 1675, Robert Hooke published the “true mathematical and mechanical form” for the shape of an ideal arch.  However, Hooke wrote the theory as an anagram, abcccddeeeeefggiiiiiiiillmmmmnnnnnooprrsssttttttuuuuuuuux. Its solution was never published in his lifetime.  What was the secret hiding … Continue reading →
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12:30 PM | 8/31/15
8 - 3 = 1 * 1 * 5Also:3√8 + 3 = 1 * 1 * 5Also:8 - 3! - 1 = 1^5
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3:55 AM | AFGL 0.1.5
I think I’m at that point about this thing where I really don’t want the whole proof. They tell me it has been proved, and I’d like to know more about it, but… this definitely feels like Someone Else’s Problem. Does that make me a bad mathematician? (the last digits don’t mean anything, of course …) So, I think I’ve figured what is the Magic Thing that Must Happen to finish Lazard’s calculation when you follow wikip’s point of […]

August 30, 2015

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10:15 PM | ergodicity of approximate MCMC chains with applications to large datasets
Another arXived paper I read on my way to Warwick! And yet another paper written by my friend Natesh Pillai (and his co-author Aaron Smith, from Ottawa). The goal of the paper is to study the ergodicity and the degree of approximation of the true posterior distribution of approximate MCMC algorithms that recently flourished as […]
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6:40 PM | The distance of the moon
Having just re-read the delightful Italo Calvino story of this name (which you can read here), I was also entranced by the following animation: Also: my take on the pronunciation of the name of the narrator: the first f is … Continue reading →
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12:30 PM | 8/30/15
8 - 3 = 0 + (1 * 5)Also:3√8 + 3 + 0 = 1 * 5
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5:20 AM | advice for would-be PhD students
I recommend the article 10 steps to PhD failure in the Times Higher. The authors are based in Canada and are in the social sciences, but their list of 10 things to avoid, is something that would be useful to many prospective doctoral students I’ve come across. The most important ones, appropriately listed first, areStay at the same universityDo an unfunded PhDChoose the coolest supervisorIn what follows, I’ll assume you have read the article, and I just add some more notes. That first item, […]

August 29, 2015

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10:15 PM | no country for ‘Og snaps?!
A few days ago, I got an anonymous comment complaining about my tendency to post pictures “no one is interested in” on the ‘Og and suggesting I moved them to another electronic media like Twitter or Instagram as to avoid readers having to sort through the blog entries for statistics related ones, to separate the […]
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7:54 PM | SUSY 2015
SUSY 2015, this year’s version of the big annual conference on supersymmetry, has been going on for the past week at Lake Tahoe. Joe Lykken began his summary talk by explaining how as a kid he was a big fan … Continue reading →
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4:31 PM | Silly season gleanings
EPSRC have finally made it into Private Eye, into Pseuds Corner to be precise; the current edition quotes part of their definition of a sandpit. (The entire definition is several pages long. Thus, sample activities for the first stage, called … Continue reading →
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2:49 PM | Meeting new people at ICFP
This afternoon I’ll be getting on a plane to Vancouver for ICFP. I’m looking forward to seeing many friends, of course, but I also enjoy meeting new people—whether or not they are “famous”, whether or not I think they can … Continue reading →
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1:08 PM | Beginning the Year with Math Journals
Last Monday marked the first day of my 2015-16 school year. It’s been an amazing week but I’m glad the weekend is here. Yesterday my school had its annual PTO picnic and I now have some time to write. I feel like I need time to process and reflect on the whirlwind of events that’ve […]
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12:30 PM | 8/29/15
8 + 2 - 9 = 1^5Also:3√8 + 2 = (9 * 1) - 5
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10:19 AM | ¡Hola mundo!
Bienvenido a WordPress. Esta es tu primera entrada. Edítala o bórrala, ¡y comienza a escribir!
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2:28 AM | Zahlen an der Börse
xkcd präsentiert in seiner neuen Zeichnung den Engineer-Syllogism, der nun ja ein wenig an den bekannten Deppen-Syllogismus erinnert (“ich verstehe nichts von Quantenmechanik, ich verstehe nichts vom Plazeboeffekt, also hat der Plazeboeffekt mit Quantenmechanik zu tun”) Es gibt übrigens eine von einem Mathematiker (Vladimir Lefebvre) entwickelte Theorie, derzufolge die Entwicklung des Börsenmarktes ausschließlich von der…

August 28, 2015

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10:15 PM | walking the PCT
The last book I read in the hospital was wild, by Cheryl Strayed, which was about walking the Pacific Crest Trail (PCT) as a regenerating experience. The book was turned into a movie this year. I did not like the book very much and did not try to watch the film, but when I realised […]
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6:53 PM | Mathematical T-Rex
Ever explained to a “working mathematician” about the undecidability of the continuum hypothesis? I bet you too had felt like this T-Rex. (Thanks to Matt Inman of The Oatmeal for the template, which can be found here.) P.S. You can expect more of these in the future.
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6:42 PM | This Week’s Hype
Bogus media stories about how “physicists finally find a way to test string theory” have now been with us for decades, with a large number of them documented here. Recently this phenomenon seemed to finally be dying down, with such … Continue reading →
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6:02 PM | Spark for Linear Algebra: don’t
Here are some pretty pictures of empirical orthogonal functions (principal components in climatology jargon) calculated for the 3D field of ocean temperatures using data collected over 32 years, generated by computing a rank 20 PCA of a 2 Tb matrix. I’ve been doing a lot of programming recently, implementing truncated SVDs in Spark on large […]
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5:43 PM | How to Properly Rinse a Water Bottle
The other day we were camping and I had to rinse my Nalgene bottle (post not sponsored by Nalgene). I only had a fixed amount of water, less than the capacity of the bottle, and I had to decide how to best use the water to minimise the concentration of contaminants. I could pour all […]
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