http://php.mandelson.org/wp2 Just another WordPress weblog Mon, 23 Aug 2010 19:26:56 +0000 http://backend.userland.com/rss092 en I finally got around to watching last week's Futurama late last night, and there's an interesting permutations puzzle involved. The puzzle itself is a minor SPOILER, so stop now if 5 days isn't enough time for you. Puzzle: There's a machine that can swap minds between bodies, but can't swap ... http://php.mandelson.org/wp2/?p=249 "Finger multiplication" is an old trick for using the bottom-left (easier to memorize) quadrant of the times table to do multiplication in the top-right quadrant. It's easy to work out why it works, but unsatisfying, but I found rederiving the technique gave more insight. How might we do this? ... http://php.mandelson.org/wp2/?p=235 I've never seen Simpson's paradox explained by showing the distributions, which I found to be very helpful in understanding what's going on. So, take a look at these two distributions I made from calls to random(): The cyan distribution has a higher mean than the magenta one, but anyone worth ... http://php.mandelson.org/wp2/?p=230 So, Vinay Deolalikar has a purported proof that P ≠ NP here. But there must be some error, because I just came up with this simple proof that P = NP ! (If you think "joke proof" sounds like an oxymoron, you can stop reading here.) Let W(m) ➙ s ... http://php.mandelson.org/wp2/?p=216 Did you read about the recent dispute about Britain refusing to admit athletes from the Nationals into the UK to play in the world lacrosse championship? (NY Times) The Nationals represent Haudenosaunee, the Iroquois Confederation, and travel on Haudenosaunee passports, which Britain refused to recognize, saying it didn't recognize them ... http://php.mandelson.org/wp2/?p=211 When explaining conditional probability, the "two child" puzzle is often brought in, which is too bad because it's a terrible example. Case in point, this recent blog post by Keith Devlin. I tell you I have two children and that (at least) one of them is a boy, and ask you ... http://php.mandelson.org/wp2/?p=199 One of the news stories from Tuesday's many primary elections which has stayed in the news is about unemployed veteran Alvin Greene trouncing unpopular member of the party machine Vic Rawl in the race for South Carolina's Democratic nominee for Senate, 59-41. Greene self-funded, meaning he used his own savings to ... http://php.mandelson.org/wp2/?p=191 Passed away yesterday, at 95. I remember Gardner's "Mathematical RecreationsGames" well, it was great at showing sides of math not seen in school. I have many of the books collecting those articles, plus others of his like Ah! Gotcha. They had a big impression on me during my formative ... http://php.mandelson.org/wp2/?p=178 I put a photo gallery from my Death Valley trip up. (Wishing for a left-handed camera...) http://php.mandelson.org/wp2/?p=177 Not my usual day, so perhaps postworthy. Last night I tried to head out to Hollywood, but my car wouldn't start. Didn't even do the "rrr-rrr" thing, and I verified I hadn't left the lights on. So much for hitting the nightlife, spent the evening online instead. This ... http://php.mandelson.org/wp2/?p=174