John Milnor

John Willard Milnor (born 20 February 1931 in Orange, New Jersey) is an American mathematician known for his work in differential topology, algebraic K-theory and low-dimensional holomorphic dynamical systems. As an undergraduate at Princeton University he was a Putnam Fellow in 1949 and 1950 and proved the Fáry-Milnor theorem at the age of 19. He received his doctorate at Princeton in 1954 under Ralph Fox with a dissertation on isotopy of links, in which he introduced the invariants now called Milnor invariants. He is a distinguished professor at Stony Brook University and the only mathematician to have won the Fields Medal, the Wolf Prize, the Abel Prize and all three Steele Prizes.