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# Posts

### March 10, 2014

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What Peirce is attempting to do in CP 3.75 is absolutely amazing and I personally did not see anything on a par with it again until I began to study the application of mathematical category theory to computation and logic, back … Continue reading →
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I received this email yesterday: I have been using your ‘forecast’ package for more than a year now. I was on R version 2.15 until last week, but I am having issues with lubridate package, hence decided to update R version to R 3.0.1. In our organization even getting an open source application require us to go through a whole lot of approval processes. I asked for R 3.0.1, before I get approval for 3.0.1, a new version of R ( R 3.0.2 ) came out. Unfortunately for me forecast package was […]

### March 09, 2014

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I’m pleased to announce that this week we’ll be reporting on the 2014 Simons Symposium — Discrete Analysis: Beyond the Boolean Cube. This is the second of three biannual symposia on Analysis of Boolean Functions, sponsored by the Simons Foundation. You may remember our reports on the 2012 edition which took place in Caneel Bay, [...]
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Last week I had the pleasure of giving a talk at a workshop for the new Initiative for Mathematical Sciences and Engineering at UIUC.  It was a very interesting visit, especially given the similar perspective of the initiative to the Computing and Mathematical Sciences PhD program we are starting next year at Caltech.  I really […]
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I finally had a chance to visit Yale, which (by various orderings) is the fanciest US university at which I had never given a talk (nor even visited). The town itself struck me, at first, as a cross between Oxford … Continue reading →
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Source Transcript Kapitel 2 Dicke Teilmengen von $S$ Def: $T\subseteq S$ dick <=$\{ x^{-1}T : x\in S \}$ hat eDe Prop: Aeq: (a) $T$ dick; (b) $\forall e \subseteq_e S \exists y \in S: ( y \in … + We continue with §3. Application of the Algebraic Signs to Logic. The Signs for Multiplication (cont.) The sum generally denotes no logical term. But may be considered as denoting some two ’s. It is natural to write: and … Continue reading → + Because it’s been a while since I posted a photo. The weather has not been cooperating recently, so instead here’s one from the archives. + Alexi Onatski has a fine recent paper, "Asymptotic Analysis of the Squared Estimation Error in Misspecifi ed Factor Models." There's also an Appendix.Four interesting cases have emerged in the literature, corresponding to two types of data-generating process (exact factor structure -- diagonal idiosyncratic covariance matrix vs. approximate factor structure -- non-diagonal idiosyncratic covariance matrix) and two modes of asymptotic analysis (strong factor structure vs. weak -- see […] + Cantami, o diva di una dama che era stata rapita, ma che non era poi una dama, nel senso umano del termine, ma una mitica dama magica, in grado di moltiplicare il chicco di riso che viene posto sul primo dei suoi quadretti (un po' come la leggendaria scacchiera):Il nostro eroe, però, preso da collera fiera e tremenda, mandò in 64 pezzi sulla testa del rivale la preziosa dama. Per ripristinare il magico potere della dama, però, bisogna ricostruire la dama con la stessa disposizione originale […] + The Penrose process is a process theorised by Roger Penrose wherein energy can be extracted from a rotating black hole. That extraction is made possible because the rotational energy of the black hole is located, not inside the event horizon of the black hole, but on the outside of it in a region of the Kerr spacetime called the ergosphere, a region in which a particle is necessarily propelled in locomotive concurrence with the rotating spacetime. All objects in the ergosphere become dragged by […] Reva Kay Williams (2002). The Gravitomagnetic Field and Penrose Processes, arXiv: Citation + Today I've been playing with the induced subgraphs of the Clebsch graph. Several other interesting and well-known graphs can be obtained from it by deleting a small number of vertices and forming the induced subgraph of the remaining vertices. To begin with, one simple construction of the Clebsch graph is to take all length-four binary strings as vertices, and to make two strings neighbors when they differ either by a single bit or by all four bits. So it has sixteen vertices and 40 edges, and […] + From this point forward we may think of idempotents, selectives, and zero-one diagonal matrices as being roughly equivalent notions. The only reason I say roughly is that we are comparing ideas at different levels of abstraction in proposing these connections. … Continue reading → + Any Jackie Mason fans out there? In connection with our discussion of power,and associated fallacies of rejection*–and since it’s Saturday night–I’m reblogging the following post. In February [2012], in London, criminologist Katrin H. and I went to see Jackie Mason do his shtick, a one-man show billed as his swan song to England. It was like […] ### March 08, 2014 + By way of fixing the current array of relational concepts in our minds, let us work through a sample of products from our relational multiplication table that will serve to illustrate the application of a comma relative to an absolute … Continue reading → + Solo per tranquillizzarvi, anche io come molte donne oggi, 8 marzo, sono andata dal parrucchiere. Il mio parrucchiere di fiducia abita con me e sa usare la macchinetta per capelli benissimo!Guardare per credere! + Rejected postsFiled under: rejected post + Oggi, 8 marzo, giorno conosciuto soprattutto come 'festa' delle donne. In realtà si tratta della giornata internazionale della donna, che suona meglio a mio parere, perché non c'è proprio niente da festeggiare.Ora, non mi sono mai definita una femminista, perché peccando di qualunquismo da italiano medio (quale sono) non ho mai capito a fondo cosa vuol dire femminismo. Lo so, c'è la spiegazione su wikipedia, ma a me non basta. Vorrei vedere il femminismo fuori, tra la gente, tra le donne. […] + SRI released their two-year, Gates-funded study of Khan Academy and I've read through their research brief. Regardless of what I summarize here, you should read it, too. It's an easy read and it will help you understand the limitations of the study and prevent unnecessary conclusion-jumping.Here's what I'm taking away from the research brief:Methodology: Researchers selected 20 schools and 70+ teachers across nine sites for this study, choosing a range of school types from a […] Editor's Pick + My work macbook pro recently crapped out on me during an update of the OS (apparently something has a tendency to go wrong with the video card or its driver or something similar during this particular update for this particular model … sigh) so I’ve had the joy of reinstalling my personal ecosystem of software […] + Despite the lingering snow, March is here and Pi Day is only a week away! I love Pi Day because it combines three of my favorite things: math, puns, and dessert. Baking a pie is always a fun (and tasty!) way … Continue reading → ### March 07, 2014 + Nove storie, anzi dieci, le cui protagoniste sono donne di ogni età e di ogni ceto sociale. Nove donne che si ritrovano per la prima volta insieme, nella stessa stanza e che hanno in comune la loro psicoterapeuta. Fino a quel momento ognuna ha raccontato la sua storia solo davanti la psicoterapeuta, adesso si ritrovano le une di fronte le altre ad aprirsi e raccontarsi.Un libro tutto al femminile, dove ogni donna racconta la propria storia. Sono racconti che commuovono, rallegrano, fanno […] + This happy and cheerful period on my blog would not be complete without some mention of Anton Makarenko’s “Pedagogical poem,” aka “The Road to Life.” (Full text available here.) Makarenko, in case you don’t know, was one of the founders … Continue reading → + This is a short piece I wrote for the next issue of the Oracle newsletter produced by the International Institute of Forecasters. Special section topics We continue to publish special sections on selected topics. Because of the change in the way regular papers are now handled, we do not publish whole special issues any more. Rather, each issue has regular papers at the front, and if there are any special sections they appear at the back. Lately, we had a special section in the last issue of […] ### March 06, 2014 + (da Eta Beta e la cometa al fenantrone) + As part of my talk in the JMM Baltimore session I raised the possibility of a central site for connecting Open Math initiatives. I'd like to expand on that. I worked for a time on the Comprehensive$\TeX$Archive Network (CTAN). If you write$\TeX\$-related software that you want to offer to the community, then you send it to CTAN where users can find it and where the standard distributions MiKTeX and TeX Live (as well as commercial vendors) can also find it. I saw there the advantage of […]
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We’re now well into the last third of my Networks course, which focuses on the interaction of economics and networks.   We talk about a lot of different topics, but one that the students really seem to enjoy is ad auctions, which tends to take up the last three or four lectures of the class — […]
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As in the previous post, all computations here are at the formal level only. In the previous blog post, the Euler equations for inviscid incompressible fluid flow were interpreted in a Lagrangian fashion, and then Noether’s theorem invoked to derive the known conservation laws for this equation. In a bit more detail: starting with Lagrangian […]
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Michel Goemans and David Williamson made a splash in the 90's using semidefinite programming to give a new approximation algorithm for the max-cut problem, a ratio of 2θ/(π(1-cos(θ)) minimized over θ between 0 and π, approximately 0.87856. Hard to believe that this ratio is tight, but it is assuming the unique games conjecture. Optimal Inapproximability Results for MAX‐CUT and Other 2‐Variable CSPs? by Subhash Khot, Guy Kindler, Elchanan Mossel and Ryan O’Donnell Noise stability of […]
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I have an awkward relationship with mathematical oncology, mostly because oncology has an awkward relationship with math. Although I was vaguely familiar that evolutionary game theory (EGT) could be used in cancer research, mostly through Axelrod et al. (2006), I never planned to work on cancer. I wasn’t eager to enter the field because I […]

Michor, F., Hughes, T., Iwasa, Y., Branford, S., Shah, N., Sawyers, C. & Nowak, M.A. (2005). Dynamics of chronic myeloid leukaemia, Nature, 435 (7046) 1267-1270. DOI:

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