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Posts

July 25, 2014

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12:42 PM | Officially an archaeologist !?
An article I coauthored with Daniel Henderson, Anvar Shukurov, Richard Boys, Graeme Sarson and Andrew Golightly: Regional variations in the European Neolithic dispersal: role of the coastlines has been accepted for publication in Antiquity, a leading archaeology journal. 

July 24, 2014

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11:54 PM | Need some book reviewed- faster than usual
I have been the SIGACT NEWS book review editor since 1997. I have tried to get about 10 books reviewed per column. I have succeeded- perhaps too well! I have gotten so many reviews out that I only have six reviews left. I DO have many books that could be reviewed, and that is where YOU come in! List of books available for review: Here Advice for reviewers: Here LaTeX  Template for reviews: Here ALL of my prior columns: Here IF you want to review a book DO NOT leave a comment- just […]
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9:41 PM | Category theory in two sentences
Tom Leinster’s book Basic Category Theory  arrived today on the new book shelves at the CUP bookshop.  I just love the opening two sentences, which seem about as good a minimal sketch of what category theory is up to as … Continue reading →
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8:50 PM | Why Do Americans Stink at Math? – an NYTimes Article
In school, did you “learn” mathematics by just memorizing some facts and not really understanding where those facts arose? Karen Morgan Ivy Tweeted the below Calvin and Hobbes comic. Is Mathematics an art or a science? Calvin has a different … Continue reading →
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6:36 PM | Emanuele Viola presents: “behind the paper”
Emanuele Viola started a new series of posts which is related to the research life-stories project. In his words: “the series “behind the paper” collects snapshots of the generation of papers. For example, did you spend months proving an exciting bound, only to discover it was already known? Or what was the key insight which made […]
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1:03 PM | Quantization as Deformation
Very early in my study of physics, Weyl became one of my gods. I use the word “god” rather than, say, “outstanding teacher” for the ways of gods are mysterious, inscrutable, and beyond the comprehension of ordinary mortals.                                       […]
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9:47 AM | Mathematicians' intuitions - a survey
I'm passing this on from Mark Zelcer (CUNY): A group of researchers in philosophy, psychology and mathematics are requesting the assistance of the mathematical community by participating in a survey about mathematicians' philosophical intuitions. The survey is here: http://goo.gl/Gu5S4E. It would really help them if many mathematicians participated. Thanks!
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7:48 AM | No uniform ultrafilters
Earlier this morning I received an email question from Yair Hayut. Is it consistent without the axiom of choice, of course, that there are free ultrafilters on the natural numbers but none on the real numbers? Well, of course that the answer is negative. If $\cal U$ is a free ultrafilter on $\omega$ then $\{X\subseteq\mathcal […]
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2:03 AM | Coherent population forecasting using R
This is an example of how to use the demography package in R for stochastic population forecasting with coherent components. It is based on the papers by Hyndman and Booth (IJF 2008) and Hyndman, Booth and Yasmeen (Demography 2013). I will use Australian data from 1950 to 2009 and forecast the next 50 years. In demography, “coherent” forecasts are where male and females (or other sub-groups) do not diverge over time. (Essentially, we require the difference between the groups to be […]
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12:50 AM | Big grids in outerplanar strict confluent graphs
I was wondering whether the outerplanar strict confluent drawings I studied in a Graph Drawing paper last year had underlying diagrams whose treewidth is bounded, similarly to the treewidth bound for the usual outerplanar graphs. The confluent graphs themselves can't have low treewidth, because they include large complete bipartite graphs, but I was hoping that a treewidth bound for the diagram could be used to prove that the graphs themselves have low clique-width. Sadly, it turns out not to […]

July 23, 2014

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6:55 PM | Continued:”P-values overstate the evidence against the null”: legit or fallacious?
Since the comments to my previous post are getting too long, I’m reblogging it here to make more room. I say that the issue raised by J. Berger and Sellke (1987) and Casella and R. Berger (1987) concerns evaluating the evidence in relation to a given hypothesis (using error probabilities). Given the information that this hypothesis H* was randomly […]
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4:20 PM | Fifty years of CP violation
via @CERN http://t.co/9Rac42mBVh #CPviolation #CPsymmetry #matter #antimatter The CP violation is a violation of the CP-symmetry, a combination between the charge conjugation symmetry (C) and the parity symmetry (P). CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle, and then its spatial coordinates are inverted.The CP violation is discovered in 1964 by Christenson, Cronin, Fitch, and Turlay (Cronin and Fitch awarded the Nobel […]

Christenson, J., Cronin, J., Fitch, V. & Turlay, R. (1964). Evidence for the 2π Decay of the K_{2}^{0} Meson, Physical Review Letters, 13 (4) 138-140. DOI:

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7:57 AM | Plotting the characteristic roots for ARIMA models
When modelling data with ARIMA models, it is sometimes useful to plot the inverse characteristic roots. The following functions will compute and plot the inverse roots for any fitted ARIMA model (including seasonal models). # Compute AR roots arroots <- function(object) { if(class(object) != "Arima" & class(object) != "ar") stop("object must be of class Arima or ar") if(class(object) == "Arima") […]
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3:19 AM | The human factor
A recent Telegraph article suggests that “females, as a whole, are not hugely engaged by science.” Emphasis mine: The problem with science is that, for all its wonders, it lacks narrative and story-line. Science (and maths) is about facts, and … Continue reading →
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12:45 AM | El Nino Project (Part 6)
guest post by Steven Wenner Hi, I’m Steve Wenner. I’m an industrial statistician with over 40 years of experience in a wide range applications (quality, reliability, product development, consumer research, biostatistics); but, somehow, time series only rarely crossed my path. Currently I’m working for a large consumer products company. My undergraduate degree is in physics, […]

July 22, 2014

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7:47 PM | Chinese Diebold-Rudebusch Yield Curve Modeling and Forecasting
A Chinese edition of Diebold-Rudebusch, Yield Curve Modeling and Forecasting: The Dynamic Nelson-Siegel Approach, just arrived. (I'm traveling -- actually at IMF talking about Diebold-Rudebusch among other things -- but Glenn informed me that he received it in San Francisco.) I'm not certain that I even knew it was in the works. Anyway, totally cool. I love the "DNS" ("Dynamic Nelson-Siegel") in the Chinese subtitle. Evidently some things just don't translate. Not sure how/where to buy it; […]
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4:44 PM | PageRank beyond the Web
I just completed a survey article about uses of PageRank outside of web-ranking. The paper has been submitted to a journal, and I also posted the manuscript to arXiv. David F. Gleich. PageRank beyond the Web. arXiv. cs.SI:1407.5107, 2014. The … Continue reading →
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4:06 PM | Rigor + Relevance beyond Caltech
I’ve been busy traveling for most of the last month, and so missed my chance for timely postings about a couple of exciting happenings that highlight how theory can impact practice. But, here are two that I can’t resist a quick post about, even if it is a bit late. First, this year’s ACM SIGCOMM […]
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3:42 PM | The Burden of Large Enrollments
This week I'm at the CRA Snowbird conference, the biennial meeting of CS chairs and other leaders in the field. In 2012 many of the discussion focused on MOOCS. This year the challenge facing most CS chairs are booming enrollments in CS courses. A nice problem to have, but a problem nevertheless. Last night we had a broad discussion about the burgeoning number of students. Ed Lazowska showed his NCWIT slides giving anecdotal evidence. It's too early to get a complete survey of CS […]
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2:43 PM | Gods, phylosophy and computers
by @ulaulaman http://t.co/Q3AODpvKAs #Godel #ontologicalproof #god #computer The ontological arguments for the existence of God was introduced for the first time by St. Anselm in 1078: God, by definition, is that for which no greater can be conceived. God exists in the understanding. If God exists in the understanding, we could imagine Him to be greater by existing in reality. Therefore, God must exist.There are a lot of phylosophies, mathematics and logicians that proposed their ontological […]

Christoph Benzmüller & Bruno Woltzenlogel Paleo (2013). Formalization, Mechanization and Automation of Gödel's Proof of God's Existence, arXiv:

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2:01 PM | Lambda calculus and the fixed point combinator in chemlambda (VI)
This is the 6th  (continuing from part I  and part II  and part III and part IV and part V)   in a series of expository posts where we put together in one place the pieces from various places about: how is treated lambda calculus in chemlambda how it works, with special emphasis on the […]
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12:59 PM | Two weeks of Art
I helped host some slovak artists in Santa Cruz area: Erik (big guy, drawing from huge swath of themes for his large paintings), Zuzana (her every move is dance), Fero (plays piano, even moving ones), Lucia (layers ornamental motifs behind the grit), Matej (graphic designer utterly open to new possibilities), Lenka (do it all herself designer), Veronika (an empathetic observer of a visual artist). All incredible in their ways, and each able to morph their working conditions, styles and themes […]
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12:16 PM | New Story
At the end of a long week of work, art and what is life, I got home. Took out the largest pot I had, filled it with water, boiled it and watched Spaghetti slide in, adding some oil and salt. I took the largest pan I had and made the sauce: tonno, chick peas, plum tomatos, garlic, and some eccentric ginger. Then I took the biggest bowl I had, heaped as much Spaghetti as I could and as much sauce as it would take, and ate it, bowl after bowl, each with teaser shavings of Parmigiano.  That […]
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11:42 AM | I sotterranei
Devo dire che con questo libro Jack mi ha un po' sfidata, non per i contenuti ma per come è scritto: soprattutto nella prima parte si poteva incontrare un punto (in senso di punteggiatura) anche dopo una pagina e mezza, e in quella pagina e mezza passare da diversi eventi, incontri, situazioni. Una sfida che ho accolto e apprezzato, perché è una bella storia d'amore ma senza troppi fronzoli (forse è proprio l'assenza di fronzoli che ai tempi questo libro non fu ben accolto dalla critica, […]

July 21, 2014

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11:54 PM | Using finite automata to draw graphs
The diagram below describes a finite state machine that takes as input a description of an indifference graph, and produces as output a 1-planar drawing of it (that is, a drawing with each edge crossed at most once).Indifference graphs are the graphs that can be constructed by the following process. Initialize an active set of vertices to be the empty set, and then perform a sequence of steps of two types: either add a new vertex to the active set and make it adjacent to all previous active […]
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5:41 AM | Variants of the Selberg sieve, and bounded intervals containing many primes
I’ve just uploaded to the arXiv the D.H.J. Polymath paper “Variants of the Selberg sieve, and bounded intervals containing many primes“, which is the second paper to be produced from the Polymath8 project (the first one being discussed here). We’ll refer to this latter paper here as the Polymath8b paper, and the former as the […]
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3:24 AM | I am not an econometrician
I am a statistician, but I have worked in a department of predominantly econometricians for the past 17 years. This has given me an interesting perspective on both disciplines. Last week at my research group meeting, I spoke about some of the differences I have noticed. Coincidentally, Andrew Gelman blogged about the same issue a day later. Theory-driven or data-driven Econometrics is “theory driven” while statistics is “data driven”. I discovered this in the interview for my current […]

July 20, 2014

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10:00 PM | Limits on the recent progress on matrix multiplication algorithms (guest post by Yuval Filmus)
Virginia Vassilevska Williams stunned the world of computer science by presenting the first improvement to the matrix multiplication constant in twenty years (later it was found that a more modest progress had been obtained independently and slightly earlier by Andrew James Stothers). The current world record is held by François Le Gall, who showed that […]
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5:16 PM | Lambda calculus and the fixed point combinator in chemlambda (V)
This is the 5th  (continuing from part I  and part II  and part III and part IV)   in a series of expository posts where we put together in one place the pieces from various places about: how is treated lambda calculus in chemlambda how it works, with special emphasis on the fixed point combinator. […]
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3:17 PM | Reading the sub(linear )text
Physicists are not known for finesse. “Even if it cost us our funding,” I’ve heard a physicist declare, “we’d tell you what we think.” Little wonder I irked the porter who directed me toward central Cambridge. The University of Cambridge … Continue reading →
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