Ian Grant Macdonald

Abstract Ian Macdonald was a pure mathematician whose work involved group theory, algebraic combinatorics and the theory of special functions. He is notable for his great originality and an almost infallible intuition for posing fundamental research questions, conjectures that were a driving force for work central to representation theory and the Langlands programme. He became well known for his book Symmetric functions and Hall polynomials, appreciated by combinatorialists and algebraists alike, and his identities on root systems led rapidly to the theory of representations of affine Lie algebras. In 1987 he defined in highly original work a class of two-variable polynomials associated with root systems, which are now known as Macdonald polynomials. The impact of these polynomials, both in mathematics and in theoretical physics, has been enormous.