Monthly Archives: September 2011

Advanced or just obscure?

Sometimes it’s clear what’s meant by one topic being more advanced than another. For example, algebra is more advanced than arithmetic because you need to know arithmetic before you can do algebra. If you can’t learn A until you’ve learned

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Counting magic squares

How many k × k magic squares are possible? If you start from a liberal definition of magic square, there’s an elegant result. For the purposes of this post, a magic square is a square arrangement of non-negative numbers such

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Bad science is tolerable, résumé padding is not

The Economist posted an article online this weekend about the scandal over irreproducible cancer research by Anil Potti. My colleagues Keith Baggerly and Kevin Coombes have been crying foul about this since 2007. I first blogged about it in January

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Weekend miscellany

Photography Texas drought and wildfires from Boston Globe Bastrop fire photos by Kerri West Saturnine eclipse by Cassini probe Color Crayola history Color in scientific visualization Why should scientists and engineers be worried about color? Math Prize awarded for classification

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Five interesting things about Mersenne primes

A Mersenne prime is a prime number that is one less than a power of 2. These primes are indexed by the corresponding power of two, i.e. Mp = 2p – 1. It turns out p must be prime before

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Wildfires make interesting sunsets

Wildfires 100 miles west of Houston make for interesting sunsets. Larger version Related post: Bastrop wildfire

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Normal subgroups are not transitive

The property “is a normal subgroup of” is not transitive.

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Bastrop wildfire

Smoke from the wildfires in Bastrop, Texas. Photo by Kerri West. Full-sized image here. More Bastrop photos by Kerri West here. At least two people have died in the fires and many have lost their homes. I’ve taken my daughters

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Synchronizing metronomes

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Anti-calculus proposition of Erdős

The “anti-calculus proposition” is a little result by Paul Erdős that contrasts functions of a real variable and functions of a complex variable. A standard calculus result says the derivative of a function is zero where the function takes on

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A thermonuclear word processor

“I use Emacs, which might be thought of as a thermonuclear word processor.” — Neal Stephenson From In the beginning was the command line Related posts: Giving Emacs another try Bumblebee software Personal organization software

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Bayes isn’t magic

If a study is completely infeasible using traditional statistical methods, Bayesian methods are probably not going to rescue it. Bayesian methods can’t squeeze blood out of a turnip. The Bayesian approach to statistics has real advantages, but sometimes these advantages

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Intolerant anarchists

From Jaron Lanier: Even in the places that are called anarchistic, in fact, what happens is a new kind of order, which is often very oppressive if you don’t happen to fit in. In San Francisco you can be attacked

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Loving your literal neighbor

It’s one thing to love your neighbor in the abstract. It’s quite another to love your literal neighbor. As G. K. Chesterton explains: We make our friends; we make our enemies; but God makes our next-door neighbor. … The duty

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Friday miscellany

The inculcation of systems thinking Harry Potter in 99 seconds A history of Bayes’ theorem The parable of the toaster R програмування для тих, хто прибуває з інших мов (Ukrainian translation of my intro to R notes) Richard Feynman explains

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