Derived categories: what Joe hears

Melanie Becker (via Katrin Becker) has pointed out an interesting talk showing what dogs hear when we tell them something - and analogously, what Joe hears when someone speaks about derived categories. ;-) Well, Joe is not quite the only person with this kind of hearing.

Incidentally, it has just become possible for loop quantum gravity to solve problems related to the Pythagorean theorem.