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The current puzzle is… puzzling: Given the set {1,…,N} with N<61, one iterates the following procedure: take (x,y) within the set and replace the pair with the smallest divider of x+y (bar 1). What are the values of N such that the final value in the set is 61? I find it puzzling because the […]
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Report on recent work of Yi Tang Zhang, taking us a step closer to a proof of the Twin Primes Conjecture.
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This is yet another post about the intersection of operations research and my frugality. I occasionally stop by Jimmy John’s to pick up some day-old bread for $0.50 per loaf. I purchase a loaf for each one of my kids and then let them do whatever they want with it for dinner. They love it. […]
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Cash register at Catalina Coffee: It’s a wooden frame for an iPad. The cashier flips the top over to let customers paying with a credit card to sign. Register frame created by Tinkering Monkey.
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I’m in London, where according to the Guardian we’re supposed to get half a month’s rain today. Sounds scary, doesn’t it? That makes it sound like it’s going to rain fifteen times what it does on a typical rainy day; of course it means that we’re supposed to get fifteen times what London gets on a […]
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(Cross-posted at NewAPPS)A few days ago Eric had a post about an insightful text that has been making the rounds on the internet, which narrates the story of a mathematical ‘proof’ that is for now sitting somewhere in a limbo between the world of proofs and the world of non-proofs. The ‘proof’ in question purports to establish the famous ABC conjecture, one of the (thus far) main open questions in number theory. (Luckily, a while back Dennis posted an extremely helpful and precise
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I think it’s part of my duty as a blogger to intersperse, along with the steady flow of jokes, rants, and literary criticism, some material that will actually be useful to you. So here goes. Jarno Vanhatalo, Jaakko Riihimäki, Jouni Hartikainen, Pasi Jylänki, Ville Tolvanen, and Aki Vehtari write: The GPstuff toolbox is a versatile [...]The post GPstuff: Bayesian Modeling with Gaussian Processes appeared first on Statistical Modeling, Causal Inference, and Social Science.
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Suppose you want to know when your great-grandmother was born. You can’t find the year recorded anywhere. But you did discover an undated letter from her father that mentions her birth and one curious detail: the 13-year and 17-year cicadas…Read more ›
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Every odd integer greater than 5 is the sum of three primes, says Harald Helfgott. And there are infinitely many prime gaps less than seventy million, says Yitang Zhang. (As Dan Goldston quips in this blog post from Nature, this is within a factor of thirty-five million of the target.
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A week ago I wrote about Perrin numbers, numbers Pn defined by a recurrence relation similar to Fibonacci numbers. If n is prime, Pn mod n = 0, and the converse is nearly always true. That is, if Pn mod…Read more ›
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I’ve discussed the broken business model that is the credit rating agency system in this country on a few occasions. It directly contributed to the opacity and fraud in the MBS market and to the ensuing financial crisis, for example. And in this post and then this one, I suggest that someone should start an […]
