Gerard Debreu 
[An updated version of this biography can be found at Gerard Debreu in the 2nd edition.]
Gerard Debreu's contributions are in general equilibrium theory—highly abstract theory about whether and how each market reaches equilibrium. In a famous paper coauthored with Kenneth Arrow, published in 1954, Debreu proved that under fairly unrestrictive assumptions, prices exist that bring markets into equilibrium. In his 1959 book, The Theory of Value, Debreu introduced more general equilibrium theory. He used complex analytic tools from mathematics—set theory and topology—to prove his theorems. In 1983 Debreu was awarded the Nobel Prize for his work on general equilibrium economics.
A native of France, Debreu has spent most of his professional life at the University of California at Berkeley. In 1962 he started as a professor of economics and was appointed professor of mathematics in 1975. In 1976 Debreu was made a chevalier of the French Legion of Honor.
Selected Works
(With Kenneth Arrow.) "Existence of a Competitive Equilibrium for a Competitive Economy." Econometrica 22, no. 3 (1954): 20590. Mathametical Economics: Twenty Papers of G. Debreu, edited by W. Hildenbrand. 1981. Theory of Value: An Axiomatic Analysis of Economic Equilibrium. 1959. Reprint. 1971. 

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