Two professors spent 27 years as the guys whose guess an entire corner of computer science was built on. This month a machine proved the guess wrong, and the two of them got asked to grade its homework. Back in 1999, Russell Impagliazzo and Ramamohan Paturi at UC San Diego made a bet about a logic puzzle called 3-SAT. You've got a bunch of switches you can flip on or off, plus a long list of rules they all have to satisfy at once. Trying every combination means 2^n tries for n switches, so…