Rudolph moved to
Stanford University in 1972 where revolutionary work was being done on ergodic theory. He was awarded a
Master of Science in 1973 and completed his
PhD under the supervision of
Don Ornstein in 1975, with the thesis "Non-Bernoulli Behavior of the Roots of K-automorphisms". His work in ergodic theory focused on measure theory, as opposed to the
functional analysis approach that dominated ergodic theory. His description of ergodic theory: From August 1975 to August 1976, Rudolph was a postdoctoral fellow at the
Hebrew University of Jerusalem, where he devised a solution to a problem in ergodic theory that had resisted solutions by
Ornstein and others, entitled "When are two-point extensions of Bernoulli shifts also Bernoulli shifts?". In so doing he devised the method of "nesting" which evolved into a powerful tool. He also began his studies into varieties of orbit equivalence. He became a fellow of the
Miller Institute at
U.C. Berkeley from late 1976 to 1978 and was appointed assistant professor at Stanford University from 1978 to 1981. He spent part of 1979 at the
University of Maryland where he studied
dynamics. At Maryland, he lived at "Ergodic House" with Bruce Kitchens,
Brian Marcus and Laif Swanson; they were regularly visited by
Doug Lind and Andres del Junco. In 1981 Rudolph was appointed associate professor at the University of Maryland and was awarded a
Sloan Research Fellowship. This is also where he became recognised as a world leader in ergodic theory. He was appointed professor of mathematics in 1985 and was at Maryland until 2004, at which time he was chair of the graduate program and acting chair of the Department of Mathematics. In collaboration with Janet Kammeyer and others, Rudolph developed a theory of restricted orbit equivalence which unified Ornstein’s Bernoulli theory,
Dye’s theorem,
Kakutani equivalence, and other relations into a single framework. Rudolph was also a visiting professor at several universities, including the
Pierre and Marie Curie University (1988), the Mathematics Institute of the
University of Warwick,
Nicolaus Copernicus University in Toruń (1989), the
University of North Carolina at Chapel Hill (1991),
Université d'Aix-Marseille (1993); and
Université de François Rabelais in Tours (1993). He presented several lectures, including one at the 2002 International Congress of Mathematicians in
Beijing, entitled "Applications of orbit equivalence to actions of discrete amenable groups". Rudolph and his family moved to his hometown of Fort Collins in 2005, where he was appointed to the Albert C. Yates Endowed Chair in Mathematics at
Colorado State University. There he was diagnosed with
Amyotrophic lateral sclerosis, a degenerative motor neuron disease. He founded and directed the SPIRAL program at Maryland, an intensive six-week preparation for graduate studies in mathematical sciences. It was acknowledged by the
American Mathematical Society with an award for "Mathematics Programs That Make a Difference" in 2008. As the disease progressed, some physical activities became impossible for Rudolph, but he continued to teach and do some departmental work, including supervising PhD students. He began a
Math circle for middle school girls with the assistance of a middle school teacher, Martha Cranor. It was later expanded to a summer Math Circles camp for middle school girls and boys. Rudolph died February 4, 2010, from complications from ALS. The April 2012 volume of the journal
Ergodic Theory and Dynamical Systems (Vol 32, Part 2) was dedicated to him. One of his last papers was a joint work with
Benjamin Weiss and
Matthew Foreman in the journal
Annals of Mathematics on the conjugacy equivalence relation of automorphisms. == Selected publications ==