An economist, Debreu studied the “invisible hand” described by 18th century economist Adam Smith: supply and demand, which was long talked about but never proven. So Debreu went to work on it, using mathematical models to, yes, prove that market prices regulate supply and demand; his innovative models are still used today.
“He really was the most important contributor to the development of formal math models within economics,” says University of California (Berkeley) Professor Robert Anderson. “He brought to economics a mathematical rigor that had not been seen before.” Debreu’s work had a “profound and unsurpassed effect on the choice of methods and analytic techniques in economics,” said Royal Swedish Academy of Sciences when it awarded him the Nobel Prize in Economics in 1983.
Born in France, Debreu became an American citizen after World War II and taught at UC Berkeley for 30 years. He died in France December 31 after a series of strokes. He was 83.