 As of November 10, 2015, his works have been cited 8500 times, and he has an h-index of 35.From 1971 to 1979 he headed the Computer Science Department at Carnegie Mellon and led it from a critical period to eminence (see Joseph Traub digital archive at Carnegie Mellon).From 1979 to 1989 he was the founding Chair of the Computer Science Department at Columbia.