Kevin Hartnett in Quanta:
On May 19, Ashwin Sah posted the best result ever on one of the most important questions in combinatorics. It was a moment that might have called for a celebratory drink, only Sah wasn’t old enough to order one.
The proof joined a long list of mathematical results that Sah, who turned 21 in November, published while an undergraduate at the Massachusetts Institute of Technology (he posted this new proof just after graduating). It’s a rare display of precocity even in a field that celebrates youthful genius.
“He has done enough work as an undergraduate to get a faculty position,” said David Conlon of the California Institute of Technology.
The May proof focused on an important feature of combinatorics called Ramsey numbers, which quantify how big a graph (a collection of dots, or vertices, connected by edges) can get before it necessarily contains a certain kind of substructure.