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# Posts

### July 04, 2015

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A Springer book published in conjunction with the great BAYSM 2014 conference in Wien last year has now appeared. Here is the table of contents: Bayesian Survival Model Based on Moment Characterization by Arbel, Julyan et al. A New Finite Approximation for the NGG Mixture Model: An Application to Density Estimation by Bianchini, Ilaria Distributed […]
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If you want to print the “Git for philosophers” piece, I made a release of the Git version with PDF and HTML versions. Here’s the PDF of Git for philosophers.
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A small idea before the fireworks show Thoralf Skolem was a mathematician who worked in mathematical logic, set theory, and number theory. He was the only known PhD student of Axel Thue, whose Thue systems were an early word-based model of computation. Skolem had only one PhD student, Öystein Ore, who did not work in […]
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7 - √4 = 1 * 5
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Filed under: pictures, Travel Tagged: adds, Boston, Clarex, Massachusset, métro
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Γνωρίζουμε πολύ καλά ότι αν είναι τα συνηθισμένα διανύσματα βάσης στο επίιπεδο τότε κάθε διάνυσμα μπορεί να γραφεί ως: . Μπορεί δηλ. να γραφεί το ως γραμμικός συνδυασμός των όπου οι συντελεστές είναι απλά τα εσωτερικά γινόμενα με τα διανύσματα αυτά. Το ίδιο φυσικά ισχύει αν […]
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This is from an early version of Chapter 7 and from my 2009 presentation on avatars at the conference Two Streams in the Philosophy of Mathematics organized by David Corfield and Brendan Larvor.  Some of the first half has been preserved on p. 215 and there is a hint of the remainder on p. 201.  […]
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The remainder of this post has been removed, as having been based on confusion of a very-connected space with an action of $n!$ and an $n!$-equivariant image of it — the latter is very like a $\mathbf{B}n!$, and not very-connected.
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Yesterday marked the second anniversary of my blog, and today is the 239th birthday of the U.S. In celebration of Independence Day, I want to explain what matroids are. Matroids were invented by Hassler Whitney (and independently by Takeo Nakasawa) to abstract the notion of linear independence from vector spaces to a much more general […]
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I should like to argue that the axiom of determinacy is true for all games having a small payoff set. In particular, the size of the smallest non-determined set, in the sense of the axiom of determinacy, is the continuum; … Continue reading →

### July 03, 2015

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While I now try to abstain from participating to the Cross Validated forum, as it proves too much of a time-consuming activity with little added value (in the sense that answers are much too often treated as disposable napkins by users who cannot be bothered to open a textbook and who usually do not exhibit […]
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Continua la serie degli enigmi matematici da me pubblicati sulla rivista Coelum Astronomia. Nel numero di dicembre 2013 parlai di cubi, o meglio di cubi 3 × 3 × 3: un oggetto fondamentale, direi, nella storia della matematica ricreativa. Alzi la mano chi non ha mai provato, almeno una volta, a mettere in ordine il celeberrimo cubo di Rubik, geniale […]
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por Agustín Moreno En pos de contextualización, este post surgió de una discusión sobre matemática y afines con el sambita, mientras nos partiamos la boca con tremendos churrascos y un vinito en algún bar perdido de Paris. El tipo queria saber para que quiere uno las curvas holomorfas esas de las que tanto se ha […]
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por Agustín Moreno En pos de contextualización, este post surgió de una discusión sobre matemática y afines con el sambita, mientras nos partiamos la boca con tremendos churrascos y un vinito en algún bar perdido de Paris. El tipo queria saber para que quiere uno las curvas holomorfas esas de las que tanto se ha […]
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At some point, I'm convinced the "conference structure" is going to fall apart.Case in point -- I haven't bought my tickets yet for SIGCOMM because, unless I'm missing something, a schedule isn't up yet, and unfortunately, because ACM has scheduled a SIG chair meeting overlapping with SIGCOMM (which I don't understand also, but perhaps beside the point), I want to see what's going on when at the conference to plan my timing.    6+ weeks out, round trip tickets from Boston to London […]
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7 - 3 + 1 = 57 = 3 - 1 + 5
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[A rather stinky piece in The Guardian today, written by a consultant self-styled Higher Education expert… No further comments needed!] “The reasons cited for this laggardly response [to innovations] will be familiar to any observer of the university system: an inherently conservative and risk-averse culture in most institutions; sclerotic systems and processes designed for a […]
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Let be a graph with an edge orientation. This means that we are given , where V is the set of vertices and E a set of ordered pairs of distinct vertices representing the edges, and, for each edge an “orientation”. Simply put, an orientation on $\latex \Gamma$ is a list of length |E| consisting […]
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Subversion (SVN) est un outil informatique qui permet de gérer la collaboration sur des documents et en particulier des textes. Il automatise (jusqu’à un certain point!) la mise en commun des modifications et systématise l’archivage. Son utilisation nécessite un logiciel sur la machine de chaque collègue (“client svn”) mais aussi un logiciel (“serveur svn”) tournant […]

### July 02, 2015

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Artificial life which can be programmed __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________Filed under: Uncategorized Tagged: artificial intelligence, artificial life, chemlambda
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I have been trying to firm up my feeling for the theory of clutters. To that end, I have been working through proofs of some elementary lemmas. For my future use, as much as anything else, I will post some … Continue reading →
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Heiko Strathmann, Dino Sejdinovic, Samuel Livingstone, Zoltán Szabó, and Arthur Gretton arXived paper about Kamiltonian MCMC generated comments from Michael Betancourt, Dan Simpson and myself, which themselves induced the following reply by Heiko, detailed enough to deserve a post of its own. Adaptation and ergodicity. We certainly agree that the naive approach of using a […]
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I’m a little late to this, but Igor Pak has a list of combinatorics videos (of lectures and seminars) and an explanation of why you should watch them, why you should let people make videos of you, and so on. … Continue reading →
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Tunisia has been in the news for the wrong reasons. I sincerely hope that the people of this beautiful and hospitable country are not seriously harmed by the recent terrorist outrages. The best I can do to show my solidarity … Continue reading →
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7 - 2 = 1 * 5
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Filed under: Kids, pictures, R, Statistics, University life Tagged: cex, pch, plot, R
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… to Robert Schumacher, who passed his PhD viva this week. He has some revisions to do after a well-earned holiday. And thanks for the flowers!
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Two posts (the previous post and this post) are devoted to discussing the behavior of countable tightness in taking Cartesian products. The previous post shows that countable tightness behaves well in the product operation if the spaces are compact. In … Continue reading →
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In the previous two posts, we discuss the definitions of the notion of tightness and its relation with free sequences. This post and the next post are to discuss the behavior of countable tightness under the product operation. In this … Continue reading →