Ronald L. Graham, who gained renown with wide-ranging theorems in a field known as discrete mathematics that have found uses in diverse areas, ranging from making telephone and computer networks more efficient to explaining the dynamics of juggling, died on July 6 at his home in the La Jolla section of San Diego. The cause was bronchiectasis, a chronic lung condition, according to a statement from the University of California, San Diego, where Dr. Graham was an emeritus professor. “He created a lot of mathematics and some really pretty cool stuff,” said Peter Winkler, a mathematician at Dartmouth College. “This occurred over many years, and so it’s only now that we get to sort of look back and see all the stuff that he did.”One thing he did was develop methods for worst-case analysis in scheduling theory — that is, whether the order in which actions are scheduled wastes time. On another front, with his wife and frequent collaborator, Fan Chung, an emeritus mathematician at the University of California, San Diego, he developed the idea of quasi-random graphs, which applied numerical preciseness in describing the random-like structure of networks.

Source: International New York Times July 23, 2020 16:07 UTC