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# Posts

### November 24, 2014

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1. Login as root, create a file as vim /etc/init.d/McMy […]
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Warren Buffett demolishes the then conventional wisdom that stocks should perform well during periods of high inflation using simple but penetrating analysis. It is no longer a secret that stocks, like bonds, do poorly in an inflationary environment. We have … Continue reading →
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The WWW is an Internet system, based on the following ingredients: web pages (written in html) a (web) browser  a web server (because of the choice of client-server architecture) Tim Berners-Lee wrote those programs. Then the WWW appeared and exploded. The force behind this explosion comes from the separation of the system into independent parts. … Continue reading Mol language and chemlambda gui instead of html and web browsers gives new Net service? →
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Vamos con el problema semanal. Ahí va: Encuentra todas las funciones que cumplen las dos condiciones siguientes: , para todo . cuando . Que se os dé bien. Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un mensaje.Construye tú también el poliedro de Császár.Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un […]
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Miquel DuránFernando Blasco¿Es posible aprender ciencia mientras se hace magia? ¿Es posible que en una conferencia científica tengan cabida trucos de Magia? ¿Pueden un químico y un matemático dar una charla al alimón? Está claro que no siempre. Pero si se junta gente como Miquel Durán y Fernando Blasco, eso y mucho más es posible. Pues esto es lo que va a ocurrir el próximo jueves. Como parte del Programa de Actividades de la de la Facultad de Matemáticas de la Universidad de […]
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It used to be the case, 10 or so years ago, that William Stein maintained a website with extensive tables of -expansions of modular forms, computed using magma. However, as the edifice of civilization begins to crumble, this website no … Continue reading →
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No, not 120 miles north, but several thousand miles west to Banff, Canada, home of the Banff International Research Station for Mathematical Innovation and Discovery. I travelled south from St Andrews to London yesterday. We went first class; the cost … Continue reading →
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In analytic number theory, an arithmetic function is simply a function from the natural numbers to the real or complex numbers. (One occasionally also considers arithmetic functions taking values in more general rings than or , as in this previous blog post, but we will restrict attention here to the classical situation of real or […]

### November 23, 2014

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Recently, longtime friend-of-the-blog Greg Kuperberg wrote a Facebook post that, with Greg’s kind permission, I’m sharing here. A parable about pseudo-skepticism in response to climate science, and science in general. Doctor: You ought to stop smoking, among other reasons because smoking causes lung cancer. Patient: Are you sure? I like to smoke. It also creates jobs. […]
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In a cross-validated forum exchange, I used the code below to illustrate the working of an ABC algorithm: Hence I used the median and the mad as my summary statistics. And the outcome is rather surprising, for two reasons: the first one is that the posterior on the mean μ is much wider than […]
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Suppose we have a $2\times 2$ matrix $$M = \begin{pmatrix} x_{11} & x_{12}\\ x_{21} & x_{22} \end{pmatrix}$$ with entries in a field $F$. The characteristic polynomial of this matrix is $p(t) := {\rm det}(tI_2 – M) = t^2 – (x_{11} + x_{22})t + x_{11}x_{22} – x_{21}x_{12}$. One might ask: how can we produce […]
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Mona Chalabi and Andrew Flowers figure out the most common name in America, using some data by Lee Hartman to correct for the fact that first name and last name are not independent, but tend to cluster based on ethnicity. … Continue reading →
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This is a jubilee year.* In November 1964, John Bell submitted a paper to the obscure (and now defunct) journal Physics. That paper, entitled “On the Einstein Podolsky Rosen Paradox,” changed how we think about quantum physics. The paper was … Continue reading →
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This week I visited Washington University in St. Louis to give a colloquium, and caught up with a couple of my old foliations friends, namely Rachel Roberts and Larry Conlon. Actually, I had caught up with Rachel (to some extent) … Continue reading →
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Next week I’ll be giving a lecture on spectral sequences in algebraic geometry, and in the notes I’m preparing I wanted to put the spectral sequence below the title of the corresponding section in the table of contents. The \addcontentsline command was known to me, but \addtocontents wasn’t, and there is one caveat in using […]
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Fourth grade students started to explore fraction computation last week. Since the beginning of the year they’ve been periodically reviewing how to add and subtract simple fractions. About a month ago this same group of students used fraction pieces of a pie to show a visual model of adding/subtracting different fraction less than one. Last […]
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1 + 1 = 2 = 3 - 1 = √4 Also: (1 + 1) / 2 = (3 + 1) / 4 Also: 1 + 1 + 2 - 3 = 1^4
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Dimetilsulfuro ha ganado el Premio Bitácoras 2014 en la categoría “Mejor Blog de Ciencia”. En la ceremonia de entrega de premios, celebrada el pasado viernes, Deborah García Bello recibió el galardón en esta categoría en la décima edición de estos premios. Enhorabuena Deborah. En este enlace podéis ver la lista completo de ganadores en todas […]Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o […]
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Classical statistics always had difficulties with testing composite hypothesis. The theory of testing admits some fairly realistic applications bu the present state of statistics is such that the theory of testing is invoked more often than not in problems on … Continue reading →
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Spiegel Online’s “Unispiegel” macht heute mit folgendem Foto auf (es geht um den Link zu diesem Interview): Kann mir jemand erklären, was hier gerechnet wird? axb=(-2)+4(5”)-?? (Ich hatte das erst als Rätselfrage mit mehreren Antwortmöglichkeiten einstellen wollen, so wie hier oder hier, aber mir sind dann leider keine passenden Antwortalternativen eingefallen.)

### November 22, 2014

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I had a great time during this short visit in the Department of Statistics, University of Florida, Gainesville. First, it was a major honour to be the 2014 recipient of the George H. Challis Award and I considerably enjoyed delivering my lectures on mixtures and on ABC with random forests, And chatting with members […]
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Last Friday morning (the 14th) it was unseasonably cold in Atlanta. On the way to work I noticed my car’s display giving the following temperature readings: 28, 30, 32, 34, 36 – all in Fahrenheit. It somehow knew to avoid … Continue reading →
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1 * 1 * 2 * 2 * 1 = 4 Also: 1 * 1 / (2 + 2) = 1 / 4 Also: 1 * 1 * 2 / 2 = 1^4 Also: 1 + 1= 2 = 2 = 1 * √4
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I am looking for a PhD student in mathematics. Full tuition & stipend will be provided for a period of three years, which is also the official length of the programme. The topic of research is somewhat flexible and varies from constructive models of homotopy type theory to development of a programming language for a […]
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The Poynting vector represents energy in the electromagnetic fields and is given by     Students often read it as the “pointing vector”, but Poynting was a person, not a direction. Here are his own words. A SPACE containing electric … Continue reading →
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A fortnight in St Andrews was intended to be a little rest after a busy few months. It didn’t work out that way. Several mathematical things which I will report on later, including a visit from my collaborator Celia Glass … Continue reading →
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Many problems and results in analytic prime number theory can be formulated in the following general form: given a collection of (affine-)linear forms , none of which is a multiple of any other, find a number such that a certain property of the linear forms are true. For instance: For the twin prime conjecture, one […]

### November 21, 2014

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I took the opportunity of my weekend trip to Gainesville to order a pile of books on amazon, thanks to my amazon associate account (and hence thanks to all Og’s readers doubling as amazon customers!). The picture above is missing two  Rivers of London volumes by Ben Aaraonovitch that I already read and left at […]
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Sólo una breves líneas para recordaros que la próxima edición del Carnaval de Matemáticas, la Edición 5.8 Betty Scott, se celebrará del 23 al 30 de noviembre (vamos, la próxima semana) en el blog Tocamates.Esta edición estará dedicada a la matemática y estadística  americana Elizabeth Scott que el próximo 23 de noviembre cumpliría 97 años.Para participar en esta edición, hay que hacer lo de siempre:Publicar, entre el 23 y el 30 de noviembre algún contenido que […]
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Some notes about Hindley-Milner in #chemlambda . It turns out that is pretty simple to do something very intuitive. The starting point is the mol file which encodes a graph molecule. Let me recall how this works. The ingredients of a molecule are some nodes, which have ports. Nodes can be red, green, yellow or … Continue reading Hindley-Milner for chemlambda →