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December 20, 2014

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이번 금요일 동작역을 탐방했다. 매번 4호선을 타고 강남쪽으로 넘어갈 때 마다 동작대교를 지나가는데.. 나중에 꼭 카메라 들고 와 봐야지~ 했는데 이제서야 방문.   동작역 근처 반포한강시민공원에서 바라본 동부이촌동 야경이다. 오른쪽에 남산타워까지 보이는데 뭔가 방해되는 공사중인 높은 건물이 가로막고 있어서 남산타워는 … Continue reading →Related Posts ?[M2 […]
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No summary available for this post.

December 19, 2014

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Personal post triggered by the coincidence of the year’s end and a round number of posts here: 500. I started this year with high hopes about the project described in the article GLC actors, artificial chemical connectomes, topological issues and knots. Louis Kauffman wrote in the introduction some unbelievably nice words about graphic lambda calculus: … Continue reading 500: a year review at chorasimilarity, first half →
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There are many ways to define the propery of semisimple for a ring \$R\$. My favourite is the “left global dimension zero approach”: a ring \$R\$ is left semisimple if every left \$R\$-module is projective, which is just the same thing as saying that every left \$R\$-module is injective. In particular, ideals are direct summands, […]
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The annual meeting of the British Ecology Society last week was unusual in a couple of ways: it was held in France, as a joint meeting with Societé Française d’Écologie; and, for the first time since I started going in the late 1990s, I wasn’t there. Rather than throw an almighty sulk about the injustice of this, I followed #BESSfe on Twitter as best I could, and felt I got a reasonable flavour of the conference - minus the hangovers, as an... Read more

December 18, 2014

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[One can tell it’s reviewing and letter-writing season when I escape to blogging more often..] There’s been some discussion on the NIPS experiment, enough of it that even my neuro-scientist brother sent me a link to Eric Price’s blog post. The gist of it is that the program chairs duplicated the reviewing process for 10% of the […]
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Our work on bundles of quantised vortex rings in finite temperature superfluid helium has been published in Physical Review B: http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.224514
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The organisers are delighted to announce a provisional programme and call for registration for the upcoming Symposium in the Foundations of Mathematics, to be held at the Institute of Philosophy in London on 12-13th January 2015. There will be an additional (free) affiliated talk by Benedict Eastaugh at the Institute on the 14th January.Sponsors: The Institute of Philosophy, Mind Association, British Logic Colloquium, Aristotelian Society, British Society for the Philosophy of Science, and […]
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No summary available for this post.
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In 2000, Neil Armstrong gave a compelling speech to the National Press Club where he laid out the idea that the 20th century could, in some sense, be thought of as “the engineered century.”  (PhD Comics has a great illustration of excerpts from the speech.)  In particular, engineering came into its own during the 20th […]
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The NIPS (machine learning) conference ran an interesting experiment this year. They had two separate and disjoint program committees with the submissions split between them. 10% (166) of the submissions were given to both committees. If either committee accepted one of those papers it was accepted to NIPS. According to an analysis by Eric Price, of those 166, about 16 (about 10%) were accepted by both committees, 43 (26%) by exactly one of the committees and 107 (64%) rejected by both […]
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There is a one day workshop on this topic on 23 February 2015 at QUT in Brisbane. I will be speaking on “Visualizing and forecasting big time series data”. OVERVIEW Big data is now endemic in business, industry, government, environmental management, medical science, social research and so on. One of the commensurate challenges is how to […]
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Happiness. I passed my first edX course, one called Learning From Data, taught by Professor Yaser Abu-Mostafa. It was a cool course, covering the basics of machine learning and including a good chunk of mathematical info. More specifically, among other things, we went over, The perceptron learning algorithm. Differences between learning & design. When (and how) is learning feasible. The linear model. This was the first time I played around with machine learning. It was very […]
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Here is an IPython notebook with an implementation of the linear percepton algorithm. Details will follow in another post and I give a general idea of what it does in the notebook but here is what the picture looks like. Assuming that you have a set of points and you want to find a line that separates the points into different categories, this algorithm is one way to do this. It picks an initial line and moves it around the space until it finds a good separator of the set. At the end, the […]

December 17, 2014

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Today I’d like to give a fairly simple account of why Uncertainty Principles exist in quantum mechanics. I thought I already did this post, but I can’t find it now. I often see in movies and sci-fi books (not to … Continue reading →
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I spoke too soon
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In my recent posting on four-dimensional polytopes containing linked or knotted cycles of edges, I showed pictures of linked cycles in three examples, the (3,3)-duopyramid, hypercube, and (in the comments) truncated 5-cell. All three of these have some much more special properties: the two linked cycles are induced cycles (there are no edges between two non-consecutive vertices in the same cycle), they include all the vertices in the graph, and their intersection with any two- or […]
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Shu Fan and I have developed a model for electricity demand forecasting that is now widely used in Australia for long-term forecasting of peak electricity demand. It has become known as the “Monash Electricity Forecasting Model”. We have decided to release an R package that implements our model so that other people can easily use it. […]
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9.4 Error-statistical philosophy of science and severe testing Deborah Mayo has developed an alternative approach to the interpretation of frequentist statistical inference (Mayo 1996). But the idea at the heart of Mayo’s approach is one that can be stated without invoking probability at all. …. Mayo takes the following “minimal scientific principle for evidence” to […]
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When I was asked earlier this year to write a short survey on k-best enumeration algorithms for the Springer Encyclopedia of Algorithms, I wrote a first draft before checking the formatting requirements. It ended up being approximately five pages of text and seven more pages of references, and I knew I would have to cut some of that. But then I did check the format, and saw that it needed to be much shorter, approximately two pages of text and a dozen references. I don't regret doing it this […]
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Kevin Ford, Ben Green, Sergei Konyagin, James Maynard, and I have just uploaded to the arXiv our paper “Long gaps between primes“. This is a followup work to our two previous papers (discussed in this previous post), in which we had simultaneously shown that the maximal gap between primes up to exhibited a lower bound […]

December 16, 2014

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Ignaz Philipp Semmelweis, nato l'1 luglio del 1818, è stato un medico ungherese che ha portato a termine il primo studio epidemico della storia della medicina. Il suo problema fu l'ostracismo della comunità medica dell'epoca, che, ufficialmente, non gradì i suoi metodi poco rispettosi dell'autorità costituita. Semmelweis venne nominato assistente del professor Johann Klein nella Prima Clinica Ostetrica dell'Ospedale Generale di Vienna il 1° luglio, 1846. I suoi compiti erano di esaminare i […]
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The number theory behind why you can't have both perfect fifths and perfect octaves on a piano keyboard (with bonus lattice quotient music theory link; G+)Sad news of Rudolf Halin's death (G+)Frankenstein vs The Glider Gun video (G+)Günter Ziegler on Dürer's solid (WP; MF; G+)Nature will make its articles back to 1869 free to share online, for certain values of "free" that you might or might not agree with (G+)Albert Carpenter's polyhedron models (G+)The only complete proof from Fermat and […]

December 15, 2014

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Last Friday in our theory reading group, Yael Kalai observed that there’s only one other woman in the room. She noticed it because in cryptography meetings, at least in the Boston area, there is a significantly higher female presence. Of course cryptography, even in Boston, still has a very lopsided gender ratio. But I think it is still […]
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In Notes 2, the Riemann zeta function (and more generally, the Dirichlet -functions ) were extended meromorphically into the region in and to the right of the critical strip. This is a sufficient amount of meromorphic continuation for many applications in analytic number theory, such as establishing the prime number theorem and its variants. The […]
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(Guest post by Andrew Childs who is now at the Univ of MD at College Park) We have recently launched a new Joint Center for Quantum Information and ComputerScience (QuICS) at the University of Maryland. This center is a partnership with the National Institute of Standards and Technology, with the support and participation of the Research Directorate of the National Security Agency/Central Security Service. QuICS will foster research on quantum information and computation. We are […]
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Durante i suoi primi passi, la relatività speciale incrociò la strada con l'elettrone e la ricerca della sua massaLa relatività speciale di Albert Einstein proponeva alcuni elementi rivoluzionari, fornendo innanzitutto una serie di strumenti matematici e di discorsi epsitemologici a supporto di una serie di osservazioni apparentemente assurde, prima fra tutte la non conservazione delle equazioni di Maxwell sotto l'azione delle trasformazioni di Galileo.Le trasformazioni di Galileo sono una […]
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In an earlier post on predictive modeling and causal inference, I mentioned my summer "reading list" for causal modeling:Re-read Pearl, and read the Heckman-Pinto critique.Re-read White et al. on settable systems and testing conditional independence.Read Angrist-Pischke.Read Wolpin, and Rust's review.Read Dawid 2007 and Dawid 2014.Get and read Imbens-Rubin (available early 2015).I'm sure I'll blog on some of the above in due course. Meanwhile I want to add something to the list: […]
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Lovely article by Martin Krieger explaining what mathematicians actually do: http://www.ams.org/notices/200410/comm-krieger.pdf “So when you are asked, What do mathematicians do?, you can say: I like to think we are just like lawyers or philosophers who explore the meanings of our everyday concepts, we are like inventors who employ analogies to solve problems, and we are like marketers who try to convince […]
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I’ve just returned from the excellent MSRI workshop which honored Michael Harris’ 60th birthday, and here is a brief summary of some of the gossip and mathematics I picked up when I was there. First, let me take note of … Continue reading →