Atle Selberg | Mathematician, 90

Atle Selberg, 90, who won mathematics' highest prizes for his work on the properties of numbers, died of heart failure Aug. 6 at his home in Princeton.

Dr. Selberg was an emeritus professor at the Institute for Advanced Study in Princeton.

A native of Norway, he first won recognition in the 1940s for his work on prime numbers - whole numbers, such as two, three, five and seven, that can be divided only by one and themselves to produce another whole number.

A theorem had already been developed explaining how prime numbers were distributed among whole numbers. But Dr. Selberg and Hungarian mathematician Paul Erdos each came up with a concept that simplified the proof.

The two argued for years over who should be given credit. Dr. Selberg published his proof in the Annals of Mathematics in 1949.

Dr. Selberg's other accomplishments included the Selberg trace formula, which was explained in a 1956 paper published in the Journal of the Indian Mathematical Society.

The next year, the International Mathematical Union cited Dr. Selberg's proof and other works when it awarded him the Fields Medal - the equivalent of a Nobel Prize for mathematics.

In 1951, he took a professorship at the Institute for Advanced Study. He retired from the institute in 1987 and became a U.S. citizen in the 1990s. - AP