Halmos photographed George Pólya (1887-1985) and Alexander Ostrowski (1893-1986) in 1958. Another photo of Ostrowski appears on page 38 of this collection, where you can read more about him.

Born in Budapest, Hungary, George (György) Pólya entered the University of Budapest (now Eötvös Loránd University) in 1905. After studying law, languages, literature, philosophy, and, finally, physics and mathematics, he received his Ph.D. in mathematics in 1912 with a thesis in geometric probability written under Leopold (Lipót) Fejér. He then spent a year studying at the University of Göttingen, Germany, with its who’s who of eminent mathematicians, and then another few months studying in Paris, before being invited byAdolf Hurwitz, then Chair of Mathematics at Eidgenössische Technische Hochschule (ETH) in Zürich, Switzerland, to join the faculty there, which he did in 1914. Pólya worked closely with Hurwitz until Hurwitz’s death in 1919.

Although he may be best known today for his contributions to mathematics teaching and learning, Pólya was a prolific and formidable researcher who made important contributions in complex analysis, probability, combinatorics, geometry, and mathematical physics. Besides writing many papers (O’Connor and Robertson of the MacTutor Archive pointed out that he published 31 papers just from 1926 to 1928), he also wrote influential books. In 1925, after years of work, Pólya and Gábor Szegő published *Problems and Theorems in Analysis, Volumes I, II* (Springer), and in 1924 Pólya began to work with G. H. Hardy and J. E. Littlewood (page 31 of this collection) on the book *Inequalities* (Cambridge, 1934). In 1940, Pólya moved to the United States and, after short stints at Brown University and Smith College, he joined the faculty at Stanford University in Palo Alto, California, where Szegő had been based since 1938. He and Szegő continued their collaboration, producing another influential book, *Isoperimetric Inequalities in Mathematical Physics *(Princeton, 1951).

In 1945, Pólya published what may be his best known book, and certainly is the one that established him as a leader in mathematics teaching and learning, *How to Solve It: A New Aspect of Mathematical Method* (Princeton), which has been translated into 17 languages. Other books on mathematical reasoning and surveys/textbooks include:

*Mathematics and Plausible Reasoning:* *Volume I,* *Induction and Analogy in Mathematics*; *Volume II, Patterns of Plausible Inference* (Princeton, 1954);
*Mathematical Discovery: On understanding, learning, and teaching problem solving: Volume I *(Wiley, 1962),* Volume II *(1965);
*Complex Variables,* with Gordon Latta (Wiley, 1974);
*Mathematical Methods in Science,* with Leon Bowden (MAA, 1977); and
*Notes on Introductory Combinatorics,* with Robert Tarjan and Donald Woods (Birkhäuser Boston, 1983).

Pólya advised at least 30 Ph.D. students at ETH and Stanford, plus one more at England’s Cambridge University, Imre Lakatos, who received his Ph.D. in 1961. Lakatos’ Ph.D. dissertation, titled “Essays in the Logic of Mathematical Discovery,” eventually became the book *Proofs and Refutations: The Logic of Mathematical Discovery* (Cambridge University Press, 1976). (Sources: MacTutor Archive, Mathematics Genealogy Project, MathSciNet, WorldCat)

Who’s That Mathematician? Images from the Paul R. Halmos Photograph Collection