Wednesday, June 1, 2016

June 01, 2016 at 11:25PM

Today I Learned: 1) In California, early-stage school building construction is exempt from environmental regulation if it is on existing school grounds and won't increase the school's population by more than 25% or 10 classrooms, whichever is smaller. 2) So there's this weird bit of notation in calculus where derivatives of functions of single variables are notated like df/dt, but partial derivatives of functions with more than one variable are written like ∂f/∂t. Why the different notation? The operator is the same, isn't it? I've now asked two people I trust to know basically everything important in math, and they have both told me they have little to no idea. The best answer I've gotten is that the ∂ is a signifier that there are other variables at play that are being held constant. To my programmer's mind, this is absolute nonsense. If you apply the "∂" operation to a function of one variable, it does *exactly the same thing* as applying the "d" operation, so why not call it the same thing? This is a weirdly non-informative TIL, but I thought it worth noting. 3) Dealing with cybercrime is a Hard Problem. Cybercriminals do the superhero thing where their real identities are secret, making them incredibly difficult to find and punish them. Moreover, cybercrime almost invariably crosses lots of national borders, which makes it really hard for any single nation's police force to track down a criminal. Crack down on drug dealers hacking passwords from a base in Russia, and they'll just up and move to China. Today I learned that the weakest link in many illegal criminal networks is the banks that process the criminals' activities. In 2010, researchers at UCSD put together a honeypot net of computers that harvested spam and followed every link they could find to try to figure out the economic topology of the organizations behind the spam. It turned out that something like 95% of all the illegal internet activity they found was running out of three banks. The next year, Microsoft went to Visa and asked them to "encourage" those banks to stop servicing the vendors that were responsible for pirated Microsoft products. This worked amazingly well, at least temporarily. Pirates have since moved on to other banks, but it still looks like banks are the weak point for cyber crime.

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