kids encyclopedia robot

Lars Ahlfors facts for kids

Kids Encyclopedia Facts
Quick facts for kids
Lars Ahlfors
Lars Ahlfors - MFO.jpg
Lars Ahlfors
Born (1907-04-18)18 April 1907
Died 11 October 1996(1996-10-11) (aged 89)
Nationality Finnish
Alma mater University of Helsinki
Known for Analytic capacity
Riemann surfaces
Quasiconformal mappings
Denjoy-Carleman-Ahlfors theorem
Ahlfors finiteness theorem for Kleinian groups
Ahlfors theory
Conformal geometry
Geometric function theory
Awards Fields Medal (1936)
Wihuri Prize (1968)
Wolf Prize (1981)
Leroy P. Steele Prize (1982)
Scientific career
Fields Mathematics
Institutions University of Helsinki
ETH Zurich
Harvard University
Doctoral advisor Ernst Lindelöf
Rolf Nevanlinna
Doctoral students Paul Garabedian
Dale Husemoller
James A. Jenkins
Albert Marden
Robert Osserman
Henry Pollak
Halsey Royden
George Springer

Lars Valerian Ahlfors (18 April 1907 – 11 October 1996) was a Finnish mathematician, remembered for his work in the field of Riemann surfaces and his text on complex analysis.

Background

Ahlfors was born in Helsinki, Finland. His mother, Sievä Helander, died at his birth. His father, Axel Ahlfors, was a professor of engineering at the Helsinki University of Technology. The Ahlfors family was Swedish-speaking, so he first attended the private school Nya svenska samskolan where all classes were taught in Swedish. Ahlfors studied at University of Helsinki from 1924, graduating in 1928 having studied under Ernst Lindelöf and Rolf Nevanlinna. He assisted Nevanlinna in 1929 with his work on Denjoy's conjecture on the number of asymptotic values of an entire function. In 1929 Ahlfors published the first proof of this conjecture, now known as the Denjoy–Carleman–Ahlfors theorem. It states that the number of asymptotic values approached by an entire function of order ρ along curves in the complex plane going toward infinity is less than or equal to 2ρ.

He completed his doctorate from the University of Helsinki in 1930.

Career

Ahlfors worked as an associate professor at the University of Helsinki from 1933 to 1936. In 1936 he was one of the first two people to be awarded the Fields Medal (the other was Jesse Douglas). In 1935 Ahlfors visited Harvard University. He returned to Finland in 1938 to take up a professorship at the University of Helsinki. The outbreak of war in 1939 led to problems although Ahlfors was unfit for military service. He was offered a position at the Swiss Federal Institute of Technology at Zurich in 1944 and finally managed to travel there in March 1945. He did not enjoy his time in Switzerland, so in 1946 he jumped at a chance to leave, returning to work at Harvard, where he remained until his retirement in 1977; he was William Caspar Graustein Professor of Mathematics from 1964. Ahlfors was a visiting scholar at the Institute for Advanced Study in 1962 and again in 1966. He was awarded the Wihuri Prize in 1968 and the Wolf Prize in Mathematics in 1981. He served as the Honorary President of the International Congress of Mathematicians in 1986 at Berkeley, California, in celebration of his 50th year of the award of his Fields Medal

His book Complex Analysis (1953) is the classic text on the subject and is almost certainly referenced in any more recent text which makes heavy use of complex analysis. Ahlfors wrote several other significant books, including Riemann surfaces (1960) and Conformal invariants (1973). He made decisive contributions to meromorphic curves, value distribution theory, Riemann surfaces, conformal geometry, quasiconformal mappings and other areas during his career.

Personal life

In 1933, he married Erna Lehnert, an Austrian who with her parents had first settled in Sweden and then in Finland. The couple had three daughters. Ahlfors died of pneumonia at the Willowwood nursing home in Pittsfield, Massachusetts in 1996.

See also

Kids robot.svg In Spanish: Lars Ahlfors para niños

  • Ahlfors finiteness theorem
  • Ahlfors function
  • Ahlfors measure conjecture
  • Beurling–Ahlfors transform
  • Schwarz–Ahlfors–Pick theorem
  • Measurable Riemann mapping theorem
kids search engine
Lars Ahlfors Facts for Kids. Kiddle Encyclopedia.