Dennis Parnell Sullivan is an American mathematician. He is known for work in topology, both algebraic and geometric, and on dynamical systems. He holds the Albert Einstein Chair at the City University of New York Graduate Center, and is a professor at Stony Brook University. He was born on February 12, 1941 Port Huron, Michigan, United States. He received his B.A. in 1963 from Rice University and his doctorate in 1966 from Princeton University. His Ph.D. thesis, entitled Triangulating homotopy equivalences, was written under the supervision of William Browder, and was a contribution to surgery theory. He was a permanent member of the Institut des Hautes Études Scientifiques from 1974 to 1997. Sullivan's contributions to the study of algebraic topology and conformal dynamics have won him a permanent place in the ranks of great mathematicians. His accomplishments since earning a bachelor's degree from Rice and a doctorate from Princeton University include co-founding what's known as the surgery method of classifying higher-dimensional manifolds and the field of rational homotopy theory. He was a recipient of Rice's Distinguished Alumni Award in 1988 and was awarded the National Medal of Science by President George W. Bush in 2006.