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Posts

October 31, 2014

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3:26 AM | Income inequality, social mobility, and sample size
Matt O’Brien at the Washington Post’s Wonkblog has an infographic that contains the following information: quintile of income distribution first second third fourth fifth % of college graduates from poor families 16 17 26 21 20 % of high school dropouts from rich families 16 35 30 5 14 This comes from a paper entitled […]
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2:38 AM | Neil White: 1945 – 2014
Guest post by Gary Gordon Those with memories of Neil White are invited to share them in the comments below. Neil White passed away on Aug. 11, 2014. Neil was an inspiring teacher and one of the key contributors to … Continue reading →

October 30, 2014

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11:14 PM | label switching in Bayesian mixture models
A referee of our paper on approximating evidence for mixture model with Jeong Eun Lee pointed out the recent paper by Carlos Rodríguez and Stephen Walker on label switching in Bayesian mixture models: deterministic relabelling strategies. Which appeared this year in JCGS and went beyond, below or above my radar. Label switching is an issue […]
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8:56 PM | Whence spectra?!
Alex Yar asked Speaking of spectra: I learned them (and related things - e.g Brown’s representability etc) from an informal student seminar, so my understanding, I feel, lacks depth and structure. What would be a good textbook-type reference? You might try the book by Elmendorf, Kriz, Mandell, and May, “Rings, Modules, and Algebras in Stable Homotopy Theory”. I’m afraid I don’t know a good textbook-type reference for spectra-as-such. The Homotopy Theory of […]
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8:20 PM | Is Shinichi Mochizuki’s work slowly being absorbed ?
While I do not speak japasese, I’ve noticed a conversation somewhere, from which it appears that : (a) Go Yamashita has a paper in preparation titled ‘A proof of abc conjecture after Mochizuki’, and he also is in the middle of a string of lectures on that topic : 18 hours of talks at RIMS […]
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8:05 PM | The darndest things
A few days ago, I was grading a Calculus quiz and came across the following statement: “the function is discontinuous at x=3 because there is an asmatope (sic)”. I thought it was hilarious, and I still marked it as correct. … Continue reading →
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7:54 PM | Topological K-theory of C*-algebras for the Working Mathematician – Lecture 1
Claude (Haim) Schochet is spending this semester at the Technion, and he kindly agreed to give a series of lectures on K-theory. This mini-course is called “Topological K-theory of C*-algebras for the Working Mathematician”. There will be seven lectures (they take place in Amado 814, Mondays 11:00-12:30): A crash course in C*-algebras. K-theory by axioms and core examples. K-theory […]
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6:44 PM | On rational surface singularities
Another PhD student in the department (she works on quadratic forms) asked me something about surface singularities, and while explaining some of its interesting aspects (McKay correspondence, Hironaka’s resolution of singularities, intersection graphs, …) I came to realise that there is something important missing from my knowledge on rational surface singularities. Sure, you can say […]
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6:32 PM | Chemlambda quines and DNA pairs, speculation
I’m staring at this space view of the walking machine described first in this post: The picture is a screenshot of the chemlambda gui available for download from this page. The .mol file of the walker is available at this link. What is this: is a walker as described in the ouroboros predecessor post, which […]
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6:15 PM | Scheduling Large and Small
I have always known that I kind of like scheduling things. I will be department chair relatively soon, and I am looking forward to making making the teaching schedules for people. When I was a kid, I would schedule fake professional basketball and baseball seasons for fun. This is a sort of macro-scheduling, and I […]
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5:34 PM | The mess we are in with scientific publishing II - Not in the Club
previous post in this series; next post in this seriesI mentioned various problems with scientific publishing in the previous post.I neglected to mention the most discussed problems like the ownership of results by private companies, the lack of free access, the uncontrolled costs, the publicly funded work by referees and editors, et cetera.Today I want to talk about another change in scientific publishing which has occurred in my lifetime. When I was young (1970) there were many fewer […]
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12:41 PM | Maths, Just in Short Words
Mathematical proofs in short words.
Editor's Pick
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12:30 PM | 10/30/14
1 + 0 + 3 + 0 = 1 * 4 Also: (1 + 0) * (3 + 0) = 1 + √4 Also: (1 + 0) * (3 + 0) = |1 - 4|
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12:09 PM | Analysis of Boolean Functions book now available for free download
I’m happy to say that I’ve finally gotten things set up so that you can download a PDF of the book. The official web address for this is http://get.analysisofbooleanfunctions.org, or you can click “DOWNLOAD THE PDF” on the blog’s main page. A small warning: On the download page, I am using a “Google form” to [...]
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11:38 AM | Visualisation of Schubert classes in Gr(2,4) and Gr(2,5)
We are still doing Chern classes in the seminar, and today I’m speaking about the multiplicative structure of the Chow ring of a Grassmannian. It’ll include some example computations, for which I prepared a little handout. Without further ado, here it is. It’s not that spectacular, and certainly not original (it is based on the […]
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10:10 AM | Schrödinger modifies the Hamilton-Jacobi equation
Quantization as an eigenvalue problem, or alternatively, the origin of Schrödinger’s Equation. In this paper I wish to consider, first the simple case of the hydrogen atom (non-relativistic and unperturbed), and show that the customary quantum conditions can be replaced … Continue reading →
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8:30 AM | ¿Qué es un radián?
El pasado mes de mayo de 2014, durante el evento que sirvió como celebración del 50 aniversario de los estudios de Matemáticas en la Universidad de Granada, Juan Medina (uno de los integrantes de la mesa sobre Matemáticas y Redes Sociales que tuve el honor de moderar) habló durante su intervención (por cierto, aquí tenéis […]Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un mensaje.Construye […]
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8:09 AM | Relevant statistics for Bayesian model choice [hot off the press!]
Our paper about evaluating statistics used for ABC model choice has just appeared in Series B! It somewhat paradoxical that it comes out just a few days after we submitted our paper on using random forests for Bayesian model choice, thus bypassing the need for selecting those summary statistics by incorporating all statistics available and […]
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4:02 AM | The more I work through Massey
alexyar: shadowpeoplearejerks: The more I realize the pedagogy in Hatcher is REALLY BAD. I still love the exercises and examples it has, but as a teaching tool it’s really sketchy and unreliable.  For example: Compare Hatcher’s proof that homotopy equivalent maps induce equivalent homomorphisms of homology groups to Massey’s.  Cubical homology though. Just…why. Seconded on Cubical homology; but of course you all know that the preferred construction of homology is as homotopy of […]

October 29, 2014

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9:30 PM | Breakthrough Prize Ceremony
There’s a story in Variety this afternoon announcing that Seth MacFarlane will be the host this year for the ceremony in Silicon Valley announcing the 2015 Breakthrough Prizes. MacFarlane was the host of the 2013 Oscars. Other celebrities there to … Continue reading →
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6:26 PM | Artwork: The Extra
About “The Extra” superimposes a symmetric joker card over a yin-yang. Where the jokers fall inside the white areas of the yin-yang, their colors are inverted. The joker itself was licensed from a vector art supplier, as was the fancy letter J. The yin-yang was created from scratch. All my work on the piece was [...]
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5:09 PM | Kloosterman paths
It was almost twenty years ago that I started drawing and looking at the graphs of Kloosterman sums (at least, that’s a likely date; I don’t remember when it began, but I put some drawings as whimsical illustrations — see, e.g., page 26 — in my PhD thesis to enliven it, and that was around […]
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3:07 PM | An Introduction to Metal for People Who Like “Good Music” Part 2
It has been 2 years since I did Part 1. That has a broader introduction which I suggest you start with. This is intended as a minor follow up. Most of the great composers since 1900 have pushed the boundaries … Continue reading →
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1:18 PM | I am cold all over…
An email from one of my Master students who sent his problem sheet (taken from Monte Carlo Statistical Methods) late: Bonsoir Professeur Je « suis » votre cours du mercredi dont le formalisme mathématique me fait froid partout Avec beaucoup de difficulté je vous envoie mes exercices du premier chapitre de votre livre. which translates as Good […]
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12:40 PM | R. Fisher on the devilish nature of acceptance procedures
Late in Fisher’s career he wrote a critique of Neyman-Pearson statisical testing. The operative properties of an acceptance procedure, single or sequential, are ascertained practically or conceptually by applying it to a series of successive similar samples from the same … Continue reading →
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12:30 PM | 10/29/14
10 + 2 - 9 = |1 - 4| Also: 10 / 2 = (9 * 1) - 4 Also: |10 - 2 - 9| = 1^4 Also: 10 = (2 + √9) * 1 * √4
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11:00 AM | Undemokratische Ingenieure?
Den digitalen Auskunftsdienst Quora gibt es eigentlich schon seit 2009, ich habe aber erst vor einigen Monaten begonnen, dort gelegentlich mitzulesen. Das Prinzip ist ähnlich wie bei mathoverflow: es werden Fragen gestellt, auf die dann Experten oder Leute, die sich berufen fühlen, eine Antwort geben und Leser können durch Abstimmung die besten Antworten an die…
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1:14 AM | Polling and the wisdom of crowds
From The Fix at the Washington Post: Americans think the Republicans will win control of the Senate. See also the New York Times’ Upshot, which references this paper by David Rothschild and Justin Wolfers. In some sense, by asking me who I think is going to win an election you’re looking at not just who […]

October 28, 2014

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11:14 PM | reliable ABC model choice via random forests
After a somewhat prolonged labour (!), we have at last completed our paper on ABC model choice with random forests and submitted it to PNAS for possible publication. While the paper is entirely methodological, the primary domain of application of ABC model choice methods remains population genetics and the diffusion of this new methodology to […]
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9:53 PM | The new look of the chemlambda gui, new downloads and a video demo of the space view
Here is a short video with a demo of the space view of chemlambda molecules and their interaction. http://www.youtube.com/watch?v=ZPzsSpkl8Fw   At this link you can download the tar archive which contains the gui I play with.  I would be grateful if as many as possible download it and spread it in as many places, not […]
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