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Posts

October 23, 2014

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10:14 PM | Feller’s shoes and Rasmus’ socks [well, Karl's actually...]
Yesterday, Rasmus Bååth [of puppies' fame!] posted a very nice blog using ABC to derive the posterior distribution of the total number of socks in the laundry when only pulling out orphan socks and no pair at all in the first eleven draws. Maybe not the most pressing issue for Bayesian inference in the era […]
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7:45 PM | Three filtrations on the Grothendieck ring of a scheme
Today’s blog post is inspired by the Chern classes seminar that we are conducting, but it takes a rather big leap from where I left off. Everything I say is based on SGA6 and Fulton–Lang’s Riemann–Roch algebra (which is a true gem I discovered). The lambda-ring associated to a scheme If you have a sufficiently […]
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3:00 PM | New Themes: Minnow and Cols
Minnow is a light, simple theme that puts your social presence front and center, while Cols is a novel theme that lets you tell your stories without the layout getting in the way.
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12:30 PM | 10/23/14
10 / 2 = (3 * 1) + √4 Also: 10 - (2 * 3) = 1 * 4 Also: 10 - 2 - 3 = 1 + 4
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10:30 AM | Qué dice exactamente el primer teorema de incompletitud de Gödel
Hace un tiempo, sobre todo a raíz de algunos textos que leí acerca de la “aplicación” de los teoremas de incompletitud de Gödel a temas con los que no tienen ninguna relación, volvió a mi cabeza la idea de hablar sobre estos teoremas en el blog. Para ello preferí intentar contar con la colaboración de […]Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un mensaje.Construye tú […]
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7:54 AM | Counting coauthors, 2
I have decided to move one step towards practising what I preach. The arXiv is now the de facto place of publication of many mathematics papers; Google Scholar recognises it, as do various other sites such as ResearchGate. So shouldn’t … Continue reading →
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6:14 AM | BibTool on the air
Yesterday night, I realised I had about 30 versions of my “mother of all .bib” bib file, spread over directories and with broken links with the original mother file… (I mean, I always create bib files in new directories by a hard link, ln ~/mother.bib but they eventually end up with a life of their […]
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4:59 AM | A New Twist on Flexagons?
For Martin Gardner’s 100th birthday Martin Gardner introduced many including myself to the joys of Discrete Mathematics. His glorious monthly column “Mathematical Games” for Scientific American included some continuous mathematics too, of course; one could center it on “Concrete Mathematics.” However, I conjecture—based on a quick flip of the several books I own of his […]

October 22, 2014

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8:55 PM | Pentaflake Chaos
Dan Anderson commented on my Pentaflake post to observe that the pentaflake can also be created by a random process, sometimes called the Chaos Game. In this game you start with an arbitrary point and dilate it toward a target point that’s randomly chosen from some set of points that you’ve established. You then dilate […]
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7:59 PM | Evoa
A very different kind of excursion last Sunday, to Evoa, a nature reserve near the Tejo estuary. Quite a drive from Lisboa: along the highway to Vila Franca, and the iron bridge which was the last bridge across the Tejo … Continue reading →
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6:17 PM | Cuckoo Filters
An upcoming paper appearing at CoNext will be of interest to any Bloom Filter user or aficionado:Cuckoo Filter:  Practically Better than Bloom(Bin Fan, David Andersen, Michael Kaminsky, Michael Mitzenmacher)Let me describe a cuckoo filter and some of what's in the paper for you.  If you want to avoid a technical discussion, all you need to know is that for reasonably large sized sets, for the same false positive rate as a corresponding Bloom filter, cuckoo filters use less space than […]
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5:08 PM | Longreads’ Best of WordPress, Vol. 7
10 of our favorite stories from across all of WordPress.
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4:48 PM | Understanding the anomaly
I’ve recently been looking at the following paper in which -TQFT anomalies are treated carefully and various old constructions of Turaev and Walker are elucidated: Gilmer, P.M. and Masbaum, G., Maslov Index, Mapping Class Groups, and TQFT, Forum Math. 25 (2013), 1067-1106. It makes me think a lot about just what the anomaly `actually means’… […]
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2:47 PM | Pentagonal knitting of abstractions
Here is a pentagonal knitting pattern done in chemlambda, as appears after 20 steps: The knitting is made of abstraction (lambda) nodes, in the middle, bordered by fanin nodes. The knitting molecule appears after 3 steps, it can be then seen at the top of the figure. The white small molecules are loops. This pattern […]
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2:29 PM | Where Do Probability Measures Come From?
Tom Avery explains a categorical construction of the concept of probability measure.
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1:26 PM | The Role of Genre in Game Interpretation
This essay is a bit late. I wrote it about three months ago, so it rehashes tons of things from the past months of posts as if they never occurred. Still, I think the example is nice. We’ve been thinking … Continue reading →
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12:30 PM | 10/22/14
(1 + 0) * 2 * 2 * 1 = 4 Also: 10 / 2 = 2 + 1 + √4
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10:01 AM | Problemas matemáticos sin resolver que cualquier niño puede entender [Conferencia]
Otro año más seguimos con nuestras conferencias de divulgación de las matemáticas.Y en este mes de octubre, le ha tocado pasarse por Sevilla a David Orden, profesor del Departamento de Física y Matemáticasde la Universidad de Alcalá autor del altamente recomendable blog Cifras y Teclas, quien el próximo martes 28 de octubre a las 18:30 horas en la Sala de Grados de la Facultad de Matemáticas de la Universidad de Sevilla, nos hablará de algunos Problemas matemáticos sin resolver que […]
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10:00 AM | Parejas en la sucesión de Fibonacci
Vamos con el problema semanal. Ahí va: Dada la sucesión de Fibonacci encuentra todas las parejas de números reales para los cuales se cumple que es un elemento de la sucesión de Fibonacci para todo natural. encuentra todas las parejas de números reales positivos que cumplen que es un elemento de la sucesión de Fibonacci […]Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un mensaje.Construye tú […]
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6:20 AM | Tomar
The Portuguese city of Tomar was founded, on the site of a Roman town, by the Knights Templar in the twelfth century. (Many businesses in the town still use the Templar name or their logo, which is also found in … Continue reading →
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2:46 AM | In Brief
The start of the academic year has a habit of bringing forth distractions, not least of all to someone as disorganized as me. So here are a few remarks in brief. The class number of is one. John Miller, a … Continue reading →

October 21, 2014

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10:14 PM | delayed acceptance [alternative]
In a comment on our Accelerating Metropolis-Hastings algorithms: Delayed acceptance with prefetching paper, Philip commented that he had experimented with an alternative splitting technique retaining the right stationary measure: the idea behind his alternative acceleration is again (a) to divide the target into bits and (b) run the acceptance step by parts, towards a major reduction […]
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10:13 PM | Simulating a bet on a whole series from bets on individual games
From Mind Your Decisions, a puzzle about gambling: Your friend wants to make an even-payoff bet on the outcome of the entire World Series. That is, he wants to make a $100 bet so that if his team is the champion he will win $100, and if his team loses he will lose all of […]
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8:51 PM | Reasoning with Multiples to Find the Mystery Number
The study of multiples and factors is ripe with opportunities to engage students in intriguing mathematical puzzles. In prior posts (When Factors Put on Their Dancing Shoes, When Factoring Gets Personal, and Open the Safe), I’ve given some examples of what can be done. Now I’d like to introduce you to another puzzle of mine called Mystery Number that focuses on […]
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12:30 PM | 10/21/14
1 + 0 + 2 + 1 = 1 * 4 Also: (10 - 2) / 2 * 1 = 1 * 4 Also: 10 / 2 = 1 * (1 + 4)
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11:00 AM | Centenario del nacimiento de Martin Gardner
Hoy 21 de octubre de 2014 se cumplen 100 años del nacimiento del gran Martin Gardner, posiblemente el principal divulgador de las matemáticas del siglo XX, que por otra parte falleció hace relativamente poco, el 22 de mayo de 2010. Aunque seguro que la gran mayoría de vosotros conocéis a Gardner creo que no está […]Entra en Gaussianos si quieres hacer algún comentario sobre este artículo, consultar entradas anteriores o enviarnos un mensaje.Construye tú […]
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10:56 AM | De intuiciones, etiquetas, Shkespeare y Alfredo
Hace poco menos de un mes, se celebró en Bilbao el evento de divulgación Naukas Bilbao 2014. En él, muchos colaboradores del blog NAUKAS.COM, impartieron charlas de 10 minutos sobre diversos aspectos científicos. Ya en su momento os anuncié las charlas que, a priori, podrían tratar de matemáticas, así que hoy lo que voy a traeros es un breve resumen de las 4 charlas que se centraron en aspectos matemáticos.El primer encuentro con las matemáticas fue de la mano de Iñaki Úcar, quien […]
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5:33 AM | Comics, literacy and self-help
Neill recently spent a week pouring out his passion and commitment to children’s comics on his blog. I thought it made remarkable reading. It is indexed on a side panel, or you can get the series from Readlists (a site … Continue reading →
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5:10 AM | A New My Sites Section
My Sites just got a new look, but more importantly, it got a technical overhaul, making the page dramatically faster and more powerful. From one central location, scan and select any of your WordPress sites or create new ones with the support of a more visual interface. Head directly to …

October 20, 2014

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10:14 PM | control functionals for Monte Carlo integration
This new arXival by Chris Oates, Mark Girolami, and Nicolas Chopin (warning: all colleagues & friends of mine!) is a variation on control variates, but with a surprising twist namely that the inclusion of a control variate functional may produce a sub-root-n (i.e., faster than √n) convergence rate in the resulting estimator. Surprising as I […]
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