Lars Valerian Ahlfors
(born April 18, 1907,
Helsinki
, Fin.?died Oct. 11, 1996,
Pittsfield
, Mass., U.S.) was a Finnish mathematician who was awarded one of the first two Fields Medals in 1936 for his work with
Riemann surfaces.
He also won the Wolf Prize in 1981.
Ahlfors received his Ph.D. from the University of Helsinki in 1932. He held an appointment there from 1938 to 1944, then went to the University of Zurich, Switz. He joined the
faculty
at
Harvard University
, Cambridge, Mass., U.S., in 1946, remaining there until his retirement.
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Numbers and Mathematics
Ahlfors was awarded the
Fields Medal
at the International Congress of Mathematicians in Oslo, Nor., in 1936. He was cited for methods he had developed to analyze
Riemann surfaces
of inverse functions in terms of covering surfaces. His principal contributions were in the theory of Riemann surfaces, but his theorems (the Ahlfors finiteness theorem, the Ahlfors five-disk theorem, the Ahlfors principal theorem, etc.) touch on other areas as well, such as the theory of finitely generated Kleinian groups. In 1929 he resolved a conjecture of Arnaud Denjoy on entire functions. Later Ahlfors worked on quasi-conformal mappings and, with Arne Beurling, on conformal invariants.
Ahlfors’ publications include
Complex Analysis
(1953); with Leo Sario,
Riemann Surfaces
(1960);
Lectures on Quasi-Conformal Mappings
(1966); and
Conformal Invariants
(1973). His
Collected Papers
was published in 1982.