These nice math people solved a big problem! People had tried to figure it out for gosh, fifty years! Then they did it. The problem was like if you had lots of apple orchards, each with different apples. Birds would fly over and poop on them sometimes. You wanted to find out which birds were pooping on what trees and also which apples on which branches were clean, and all this, over a period of time in which orchards. Tough, huh?