Lars Valerian Ahlfors, William Caspar Graustein Professor of Mathematics, died of pneumonia on Oct. 11 in Pittsfield, Mass., at the age of 89. Ahlfors won the first Fields Medal awarded by the International Mathematics Society in 1936, a quadrennial award considered equivalent, in mathematics, to the Nobel Prize. In 1979, he was awarded the prestigious Wolf Prize in Jerusalem. Ahlfors was best known for his work in complex analysis, a fundamental subject with many applications from number theory to modern physics. His textbook, Complex Analysis, first published in 1953, with new editions in 1966 and 1979, is still considered the leading text in the field. He wrote three other mathematical books and published almost 100 papers. Colleagues and students have described his work as extraordinarily elegant, and his lectures, delivered in thundering basso, as stunningly beautiful. Ahlfors was born in Helsinki, Finland, in 1907. As he often observed, his mother's death during his birth critically influenced his life. His father, a professor of mechanical engineering at the Polytechnic Institute, was attentive but stern. In the brief autobiographical note that introduced his collected papers, published in 1982, he wrote that, "As a child, I was fascinated by mathematics without understanding what it was about, but I was by no means a child prodigy. As a matter of fact, I had no access to any mathematical literature except in the highest grades. . . . The high school curriculum did not include any calculus but I finally managed to learn some on my own, thanks to clandestine visits to my father's engineering library." Ahlfors' introduction to higher mathematics, including complex analysis, came from his mentors at Helsinki University, Ernst Lindelof and Rolf Nevanlinna. At 21, Ahlfors followed Nevanlinna to the Federal Polytechnic Institute in Zurich, where he began working at a research level. There he produced his first major work, a study of asymptotic values of an entire function, based on his own new approach to conformal mapping. Self-effacingly, Ahlfors credited Nevanlinna and another teacher, George Polya, for their "considerable help." They, in turn, insisted that he publish the results solely in his own name. Thereafter, as he expressed it, "I have tried to repay my debt by never accepting to appear as coauthor with a student." In 1933, he returned to Helsinki, where he met and married Erna Lehnert, an event he described as the "happiest and most important in my life." In 1935, he began a three-year stint teaching at Harvard. Homesick, he returned to Finland in 1938. There he spent most of the war years as professor at the University of Helsinki before being invited back to Zurich in 1944. Ahlfors returned to Harvard, as full professor, in 1946 and remained until his retirement in 1977. From 1964, he occupied the William Caspar Graustein chair. Ahlfors won several honorary doctorates, including one from the University of London and one from Harvard. As is typical in mathematics, Ahlfors achieved renown from work done while in his twenties. Less typically, he continued for decades to produce highly influential work, notably his proof of the "Ahlfors finiteness theorem," published in 1964. Ahlfors is survived by his wife, Erna, who lives in Nassau, N.Y.; three daughters, Cynthia Edwards of Jumeauville, France, Vanessa Gruen of Darien, Conn., and Old Chatham, N.Y., and Caroline Mouris of Nassau, N.Y.; a brother, Axel Ahlfors of Torup, Sweden; a sister, Unga Appelqvist of Helsinki; grandchildren and great-grandchildren. Source: Harvard Gazette 1996. |