Last month, mathematicians Karen Vogtmann and Michael Borinsky posted a proof that there is a truckload of mathematical structure within a hitherto inaccessible mathematical world called the moduli space of graphs, which Vogtmann and a collaborator first described in the mid-1980s. “That’s a super hard problem. It’s amazing they were able to,” said Dan Margalit, professor in the School of Mathematics at the Georgia Institute of Technology. (Margalit did not work on the moduli space proof.)