Professor William (Bill) Parry F.R.S. (July 3 1934–August 20 2006) was an English mathematician. During his research career, he was highly active in the study of dynamical systems, and, in particular, ergodic theory, and made significant contributions to these fields. He is considered to have been at the forefront of the introduction of ergodic theory to the United Kingdom. He played a founding role in the study of subshifts of finite type, and his work on nilflows was highly regarded.
Bill Parry was born in Coventry in the West Midlands of the United Kingdom, the sixth of seven children. Although he failed the eleven-plus exam, Parry was persuaded by his mathematics teacher at Coventry Junior Technical School, specialising in metalwork and woodwork, to aim for university. To get appropriate tuition, he had to travel to Birmingham Technical College. He won a place at University College London. Following an M.Sc. at the University of Liverpool, he returned to London to study at Imperial College with Yael Dowker, obtaining his Ph.D. in 1960.
Having served in lecturing positions at Birmingham University and the University of Sussex, Parry was appointed to a readership at the recently created University of Warwick in 1968; his was the first appointment in analysis. Two years later, he gave a particularly well-received address at the Sixteenth International Congress of Mathematicians in Nice, France, and was promoted to professor.
He played a key role in the Warwick Mathematics Department, and was Chair of the Department for 2 years. The rapid rise of the Department's international reputation was due to many, among whom Parry featured prominently. His great mathematical achievements were recognized by his early election to the Royal Society in 1984; however, he rarely used the title "Fellow of the Royal Society" except to aid specific causes of interest.
Parry continued to contribute to the mathematical community and others' learning up until his death: he taught the University of Warwick's undergraduate course on ergodic theory as late as 2003.
His published works include more than 80 research articles and four books.