Ronald Lewis Graham (born October 31, 1935) is a mathematician credited by the American Mathematical Society as "one of the principal architects of the rapid development worldwide of discrete mathematics in recent years". He has done important work in scheduling theory, computational geometry, Ramsey theory, and quasi-randomness.
He is currently the Chief Scientist at the California Institute for Telecommunications and Information Technology (also known as Cal-(IT)2) and the Irwin and Joan Jacobs Professor in Computer Science and Engineering at the University of California, San Diego (UCSD).
His 1977 paper considered a problem in Ramsey theory, and gave a "large number" as an upper bound for its solution. This number has since become well known as the largest number ever used in a mathematical proof (is listed as such in the Guinness Book of Records), and is now known as Graham's number.
Graham popularized the concept of the Erdős number, named after the highly prolific Hungarian mathematician Paul Erdős (1913–1996). A scientist's Erdős number is the minimum number of coauthored publications away from a publication with Erdős. Graham's Erdős number is 1. He co-authored almost 30 papers with Erdős, and was also a good friend. Erdős often stayed with Graham, and allowed him to look after his mathematical papers and even his income.
Between 1993 and 1994 Graham served as the president of the American Mathematical Society. Graham was also featured in Ripley's Believe It or Not for being not only "one of the world's foremost mathematicians", but also "a highly skilled trampolinist and juggler", and past president of the International Jugglers' Association.
In 2003, Graham won the American Mathematical Society's annual Steele Prize for Lifetime Achievement. The prize was awarded on January 16 that year, at the Joint Mathematics Meetings in Baltimore, Maryland. In 1999 he was inducted as a Fellow of the Association for Computing Machinery. Graham, prolific mathematician and industrious human being, has won many other prizes over the years; he was one of the laureates of the prestigious Pólya Prize the first year it was ever awarded, and among the first to win the Euler Medal. The Mathematical Association of America has also awarded him both the Lester R. Ford prize which was "...established in 1964 to recognize authors of articles of expository excellence published in The American Mathematical Monthly...", and the Carl Allendoerfer prize which was established in 1976 for the same reasons, however for a different magazine, the Mathematics Magazine.
He is married to Fan Chung Graham (known professionally as Fan Chung), who is the Akamai Professor in Internet Mathematics at the University of California, San Diego. He has four children—three daughters, Ché, Laura, Christy and a son, Marc—from an earlier marriage.