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7:29 AM | SAS®: Getting Started with PROC IML

Another powerful procedure of SAS, my favorite one, that I would like to share is the PROC IML (Interactive Matrix Language). This procedure treats all objects as a matrix, and is very useful for doing scientific computations involving vectors and matrices. To get started, we are going to demonstrate and discuss the following: Creating and Shaping Matrices;Matrix Query;Subscripts;Descriptive Statistics;Set Operations;Probability Functions and Subroutine;Linear Algebra;Reading and Creating […]

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10:15 PM | ontological argument

Filed under: Books, Kids, pictures Tagged: atheism, ontological argument, xkcd

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8:12 PM | Things Have Changed

I’ve been busy with other things, but after taking a look today at various new things related to quantum gravity, I was struck by how much things have changed sociologically in that subject over the last few years. Back in … Continue reading →

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I have given the first two lectures: lecture 1 (categories of dynamical systems, basics of entropy, exercises) lecture 2 (Lyapunov exponents, Oseledets theorem, applications)

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5:01 PM | [3] is left as an exercise

the colors-to-corners assignment here is nonstandard… i.e., inconsistent with the one i’ve been using as my “base case” in earlier blog entries. so for heck sake don’t memorize ’em this way. the “algebraic” aspect here… whereby certain “vertex triples” are assigned “dual vectors” according to the scheme [1] = [0:0:1] —> {010, 100, 110} [2] […]

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3:51 PM | Generalized Fréchet filters

Just a few minutes ago I conceived a definition of generalized Fréchet filters with definition for every poset on which filters are considered (however, I have not yet calculated the class of posets for which generalized Fréchet filter is defined; it should be easy but I am busy with other business). Generalized Fréchet filter on […]

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“It is no good just finding particular instances where peer review has failed because I can point you to specific instances where peer review has been very successful,” she said. She feared that abandoning peer review would make scientific literature no more reliable than the blogosphere, consisting of an unnavigable mass of articles, most of … Continue reading A second opinion on “Slay peer review” article →

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yet another sketch from the “lectures without words” run of MEdZ. here improved with colored inks (and spoiled by flouting the “without words” rule). “binary arithmetic” is here exploited to assign *number values* to the corners; the symbol “xyz” chosen from 000, 001, 010, 011, 100, 101, 110, 111 corresponds on this model to 4x […]

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1:43 PM | Chenevier on the Eigencurve

Today I wanted to mention a theorem of Chenever about components of the Eigencurve. Let denote weight space (which is basically a union of discs), and let be the Coleman-Mazur eigencurve together with its natural map to It will do … Continue reading →

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12:18 PM | [non] Markov chains

Filed under: pictures, Running, Travel Tagged: Amsterdam, canals, chain, Holland, Markov chain, sunrise

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11:51 AM | Non tutti gli angoli retti sono congruenti

A colori uguali corrispondono oggetti uguali. Dunque un angolo maggiore di un angolo retto è congruente a un angolo retto. Ehm.

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10:30 AM | T-duality and Isometries of Spacetime

I’ve just been to an excellent seminar on Double Field Theory by its co-creator, Chris Hull. You may know that string theory exhibits a meta-symmetry called T-duality. More precisely, it’s equivalent to put strings on circles of radius and . This is the simplest version of T-duality, when spacetime has no background fields. Now suppose … Continue reading T-duality and Isometries of Spacetime →

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8:54 AM | Richard and Edward

Did I detect just a small amount of provocation at NBSAN when Vicky Gould (from York) said to Rick Thomas (from Leicester), “You got our king”? Of course, this refers to Richard III, whose bones (as you most likely know) … Continue reading →

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During the graduate workshop on moduli of curves (organized by Samuel Grushevsky, Robert Lazarsfeld, and Eduard Looijenga last July 2014), Alex Wright gave a minicourse on the -orbits on moduli spaces of translation surfaces (the videos of the lectures and the corresponding lecture notes are available here and here). These lectures by Alex Wright made […]

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An introduction to homotopy type theory for philosophers

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1:12 AM | Post-Cherylmania wrap-up

My last post was about “Cheryl’s birthday puzzle”, which recently became an internet sensation. I mentioned several additional puzzles in that post and promised solutions; here they are. Let me begin, though, with a “cryptography” variant of the Cheryl puzzle which was sent to me by my friend and puzzle guru Pete Winkler: Cheryl’s birthday […]

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It has been a year since UBC announced its very first …“president of colour”. And as of yesterday, UBC has its very first woman provost. On the surface, these look like de-facto corollaries of a post-racial, post-sexist era, at a … Continue reading →

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10:54 PM | old mole-skin sketch newly inked

here one has labeled the vertices of a cube with (“euclidean”) 3-space co-ordinates. the “origin”… we can think of it as our “point of view”… is at 000. [the “point” in 3-space usually denoted (x, y, z) is here written as “xyz”; we restrict our attention to the values in {0, 1} for these variables […]

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10:15 PM | scale acceleration

Kate Lee pointed me to a rather surprising inefficiency in matlab, exploited in Sylvia Früwirth-Schnatter’s bayesf package: running a gamma simulation by rgamma(n,a,b) takes longer and sometimes much longer than rgamma(n,a,1)/b, the latter taking advantage of the scale nature of b. I wanted to check on my own whether or not R faced the same […]

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8:29 PM | NBSAN in St Andrews

This week, during a spell of lovely spring weather and new blossom, the 20th meeting of the North British Semigroups and Applications Network was held in St Andrews, organised by Markus Pfeiffer. It was good to see old friends such … Continue reading →

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The purpose is to understand clearly what is this story about. The most simple stuff, OK? in order to feel it in familiar situations. Proceed. Chemlambda is a collection of rules about rewritings done on pieces of files in a certain format. Without an algorithm which tells which rewrite to use, where and when, chemlambda … Continue reading A comparison of two models of computation: chemlambda and Turing machines →

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4:29 PM | Fromme Sprüche I: Gedankenqualität

Hier in Korea, auch im demokratischen Süden, liest man öfter mal erbauliche Sprüche an den Wänden. Ich habe schon länger die Absicht mal ein paar Kuriositäten zu sammeln und hier im Blog vorzustellen. Heute will ich aber nur einen Spruch weitergeben, den wohl jeder Mathematiker ohne Zögern wird bestätigen können (und bei dem man sich…

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12:30 PM | 4/23/15

4 - 2 = |(3 * 1) - 5|
Also:
|4 - (2 * 3)| = √|(1 - 5)|
Also:
(4 * 2) - 3 = 1 * 5

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12:18 PM | I give an X

Filed under: Travel Tagged: elections, UK Elections 2015, United Kingdom, vote, voters apathy

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10:15 PM | capacity exceeded…

A silly LaTeX error took me a few minutes too many to solve: I defined which got me the error message that I understood as a recursive definition. So I instead pre-defined the new θ as which did not work either… After google-ing the issue, I found this on-line LaTeX Wikibook that provided me with […]

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10:04 PM | Thoughts on ToME’s Adventure Mode

I’ve done several posts explaining why I think roguelikes are a great genre of game to play. It is probable that the most important feature of a roguelike for me is permadeath. For example, see this post for reasons why. … Continue reading →

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9:11 PM | blag

one has already learned the 7-cycle sunday-monday-tuesday-wednesday-thursday- -friday-saturday-(sunday-…) as part of one’s cultural heritage as an english speaker. and it’s high time i *used* that fact in studying “fano’s rainbow” (aka “the seven-point [projective] space”). and so to each of the *positions* in the well-known “three corners, three midpoints, one center” representation of fano space, […]

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7:41 PM | 2 and 3

Here is a question I asked myself yesterday: Suppose that X is an algebraic space which has degree 2 finite etale covering X_2 —> X and a degree 3 finite etale covering X_3 —> X such that both X_2 and … Continue reading →

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Stupiti che 1 non sia primo? Scopriamo insieme perché è "solo" l'unità!Abbiamo già visto come, partendo dai numeri primi, si possa sviluppare un discorso più o meno approfondito sulle fondamenta matematiche. Altrettanto fondamentale, però, si rivela provare a rispondere alla domanda su quale sia il numero primo più piccolo. E', infatti, abbastanza noto come il numero 1 sia stato ora inserito ora escluso dalla lista dei numeri primi, ottenendo in alcuni casi lo status di più piccolo tra […]

Agargun A.G. & Fletcher C.R. (1997). The Fundamental Theorem of Arithmetic Dissected, The Mathematical Gazette, 81 (490) 53-57. DOI: http://dx.doi.org/10.2307/3618768

Crandall R. & Pomerance C.B. (2005). Primes!, Prime Numbers, Prime numbers: a computational perspective 1-82. DOI: http://dx.doi.org/10.1007/0-387-28979-8_1

Caldwell C.K. & Xiong Y. (2012). What is the smallest prime?, Journal of Integer Sequences, 15 arXiv: 1209.2007v2

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Winifred Edgerton Merrill fu la prima americana ad ottenere un dottorato in matematica presso la Columbia University nel 1886. Nella sua tesi sviluppò una rappresentazione geometrica degli infinitesimi in diversi sistemi di coordinate, utilizzando lo jacobiano per per derivare le trasformazioni tra gli integrali nei diversi sistemi.Tra matematica e astronomiaNata a Ripon, nel Wisconsin, il 24 settembre del 1862 da Emmet e Clara Edgerton, si trasferisce con la famiglia a New York intorno al […]

Kelly S.E. & Rozner S.A. (2012). Winifred Edgerton Merrill: "She Opened the Door", Notices of the American Mathematical Society, 59 (04) 504-512. DOI: http://dx.doi.org/10.1090/noti818

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Winifred Edgerton Merrill fu la prima americana ad ottenere un dottorato in matematica presso la Columbia University nel 1886. Nella sua tesi sviluppò una rappresentazione geometrica degli infinitesimi in diversi sistemi di coordinate, utilizzando lo jacobiano per per derivare le trasformazioni tra gli integrali nei diversi sistemi.Tra matematica e astronomiaNata a Ripon, nel Wisconsin, il 24 settembre del 1862 da Emmet e Clara Edgerton, si trasferisce con la famiglia a New York intorno al […]

Kelly S.E. & Rozner S.A. (2012). Winifred Edgerton Merrill: "She Opened the Door", Notices of the American Mathematical Society, 59 (04) 504-512. DOI: http://dx.doi.org/10.1090/noti818

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Direi che oggi pomeriggio è stato un bel respirare, al Palazzo Brera. Cristina Lazzeroni dell'Università di Birmingham è venuta alle 18 (come avevo scritto nel post precedente) per raccontare del bosone di Higgs, del modello standard e di materia e antimateria. E' una sperimentale presso l'esperimento LHCb al CERN, l'esperimento dedicato proprio alla ricerca su uno dei grandi misteri dell'universo: perché in esso c'è un eccesso di materia (e d'altra parte se non fosse così, non ci sarebbe […]

Aaij R., B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander & S. Ali & (2013). First Observation of CP Violation in the Decays of B_{s}^{0} Mesons, Physical Review Letters, 110 (22) DOI: http://dx.doi.org/10.1103/physrevlett.110.221601

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Per i I cieli di Brera, il 24 settembre (domani... scusate per il ritardo nell'annuncio...) alle 18 presso la Sala delle Adunanze dell'Istituto Lombardo nel Palazzo Brera sito in via Brera 28 (Milano), si terrà la conferenza La fisica delle particelle e il Large Hadron Collider: recenti sviluppi e questioni aperte: Cristina Lazzeroni ci introdurrà alla fisica delle particelle e agli studi fatti al Large Hadron Collider del Cern di Ginevra mettendo l’accento su recenti sviluppi come la
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Aad G., J. Abdallah, S. Abdel Khalek, O. Abdinov, R. Aben, B. Abi, S. H. Abidi, M. Abolins, O. S. AbouZeid & H. Abramowicz & (2014). Measurement of the Higgs boson mass from the $H\to \gamma \gamma $ and $H\to Z{Z}^{*}\to 4\ell $ channels in $pp$ collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector, Physical Review D, 90 (5) DOI: http://dx.doi.org/10.1103/physrevd.90.052004

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rmathematicus tweeted: @rmathematicus

RT @fadesingh: At the core of all well-founded belief, lies belief that is unfounded.
- Ludwig Wittgenstein

2015-04-25 18:00:14

rmathematicus tweeted: @rmathematicus

RT @jefferson_bail: Big props to @tjowens for getting IMLS funded NDP proposals online. http://t.co/RpwQHc2o5c (now I won't have to FOIA th…

2015-04-25 17:20:56

wpgaurav tweeted: @wpgaurav

YouTube Video search : Tips and Tricks http://t.co/lOqLKNmuJL

2015-04-25 17:13:37

climeguy tweeted: @climeguy

"Faculty Summer Reading Recommendations" @garystager
You missed this one http://t.co/qPjao4xUZL Jeff Richardson would like it. :-)

2015-04-25 17:13:30

srcav tweeted: @srcav

I've updated the "General Education" blogs I like page: http://t.co/NZ8RKroCiT #ukedchat #ukfechat #edchat

2015-04-25 17:11:05

rmathematicus tweeted: @rmathematicus

“@fadesingh: In case you missed my latest #histSTM column: http://t.co/uhodlGmgVc "Horrors of the East".”

2015-04-25 17:10:44

rmathematicus tweeted: @rmathematicus

RT @SlateVault: Morton's Salt pamphlet offers 100 ways to predict rain (1933) http://t.co/HZ0bTQPKKB via @UChicagoSCRS http://t.co/juQY6Dn…

2015-04-25 17:08:40

srcav tweeted: @srcav

I've updated the "Maths and Maths teaching blogs I like" page on my blog: http://t.co/vIqR2mo94l #mathschat #mathchat #ukedchat #edchat

2015-04-25 17:07:59

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