whose work included collaboration with Hardy and Littlewood, with papers on mathematical physics, geometry, complex analysis, combinatorics, and probability theory. He is perhaps best known for his contribution to mathematics education through his book How To Solve It published in its second edition in 1957 and still widely regarded half a century later as one of the best expositions of the art of doing mathematics. In a remarkably easy prose style for a book about mathematics, Polya argues that problem solving requires the study of heuristics and summarizes the problem-solving cycle in four stages: understanding the problem, devising a plan, carrying out the plan, and looking back—or ‘see, plan, do, check’.