James Nicholson has a mathematics degree from Cambridge, and taught at Harrow School for twelve years before becoming Head of Mathematics at Belfast Royal Academy in 1990. He lives in Belfast, but now works mostly with the School of Education at Durham University. He is the author of two A level Statistics texts, two GCSE Mathematics revision guides and a contributing author for a number of other mathematics textbooks. Christopher Clapham wrote the first and second editions of this dictionary. Until 1993 he was Senior Lecturer in Mathematics at the University of Aberdeen. His publications include Introduction to Abstract Algebra and Introduction to Mathematical Analysis.