Ian Nicholas Stewart (born 24 September 1945) is a British mathematician and a popular-science and science-fiction writer. He is Emeritus Professor of Mathematics at the University of Warwick, England. Education and early life Stewart was born in 1945 in Folkestone, England. While in the sixth form at Harvey Grammar School in Folkestone he came to the attention of the mathematics teacher. The teacher had Stewart sit mock A-level examinations without any preparation along with the upper-sixth students; Stewart was placed first in the examination. He was awarded a scholarship to study at the University of Cambridge as an undergraduate student of Churchill College, Cambridge, where he studied the Mathematical Tripos and obtained a first-class Bachelor of Arts degree in mathematics in 1966. Stewart then went to the University of Warwick where his PhD on Lie algebras was supervised by Brian Hartley and completed in 1969. Career and research After his PhD, Stewart was offered an academic position at Warwick. He is well known for his popular expositions of mathematics and his contributions to catastrophe theory. While at Warwick, Stewart edited the mathematical magazine Manifold. He also wrote a column called "Mathematical Recreations" for Scientific American magazine from 1991 to 2001. This followed the work of past columnists like Martin Gardner, Douglas Hofstadter, and A. K. Dewdney. Altogether, he wrote 96 columns for Scientific American, which were later reprinted in the books "Math Hysteria", "How to Cut a Cake: And Other Mathematical Conundrums" and "Cows in the Maze". Stewart has held visiting academic positions in Germany (1974), New Zealand (1976), and the US (University of Connecticut 1977–78, University of Houston 1983–84). Stewart has published more than 140 scientific papers, including a series of influential papers co-authored with Jim Collins on coupled oscillators and the symmetry of animal gaits. Stewart has collaborated with Jack Cohen and Terry Pratchett on four popular science books based on Pratchett's Discworld. In 1999 Terry Pratchett made both Jack Cohen and Professor Ian Stewart "Honorary Wizards of the Unseen University" at the same ceremony at which the University of Warwick gave Terry Pratchett an honorary degree. In March 2014 Ian Stewart's iPad app, Incredible Numbers by Professor Ian Stewart, launched in the App Store. The app was produced in partnership with Profile Books and Touch Press. Mathematics and popular science Manifold, mathematical magazine published at the University of Warwick (1960s) Nut-crackers: Puzzles and Games to Boggle the