Gerard Debreu (July 4, 1921 – December 31, 2004) was a French
economist and mathematician (In July 1975, he became a naturalized citizen of
the United States). He won the 1983 Nobel Memorial Prize in Economics.

He was born in Calais. His father was the business partner of his maternal
grandfather in lace manufacturing, a traditional industry in Calais.

Just prior to the start of World War II he finished college, but instead of
preparing for the university he studied at an improvised math curriculum in
Ambert. Later on he moved to Grenoble, both being in the so-called "Free Zone"
during World War II.

In 1941 he was admitted to the Ecole Normale Superieure with Marcel Boiteux,
which he was about to graduate from in 1944 when the D-Day made him enlist in
the Allies army. He was transferred for training to Algeria and then served in
French occupational forces in Germany until July 1945.

Debreu took the Agregation de Mathematiques at the end of 1945, and eventually
he graduated at the beginning of 1946 and later became interested in economics,
particularly the general equilibrium theory of Leon Walras. From 1946 to 1948,
he was an assistant in the Centre National de la Recherche Scientifique. These
two and a half years is the time he made the transition from Mathematics to
Economics.

In 1948, Debreu came to the USA on a Rockefeller Fellowship which allowed him to
visit several American universities, as well as those in Uppsala and Oslo in
1949-50. Debreu began working as a Research Association and joined the Cowles
Commission at the University of Chicago in the summer of 1950.

There he remained for five years, returning to Paris periodically. In 1954 he
published a breakthrough paper titled Existence of an Equilibrium for a
Competitive Economy (together with Kenneth Arrow), in which they provided a
definitive mathematical proof of the existence of general equilibrium, using
topological rather than calculus methods.

In 1955 he moved to Yale University. In 1959 he published his classical
monograph, Theory of Value: An Axiomatic Analysis of Economic Equilibrium, (Cowles
Foundation Monographs Series), which is perhaps the most important work in
mathematical economics. He also studied several problems in the theory of
cardinal utility, the additive decomposition of a utility function defined on a
Cartesian product of sets.

In this monograph, Debreu sets up an axiomatic foundation for competitive
markets. He establishes the existence of equilibrium using a novel approach. The
main idea is to show that there exists a price system for which the aggregate
excess demand correspondence vanishes. He does so by proving a fixed point like
theorem based on Kakutani's fixed-point theorem. In Chapter 7 of the book Debreu
introduces uncertainty and shows how it can be incorporated into the
deterministic model. Here he introduces the notion of a contingent commodity,
which is a promise to deliver a good should a state of nature realize. This
notion is very used in financial economics as Arrow Debreu security.

In 1960-61, he worked at the Center for Advanced Study in the Behavioral
Sciences at Stanford and devoted mostly to the complex proof that appeared in
1962 of a general theorem on the existence of an economic equilibrium.

In January of 1962, he started worked at the University of California, Berkeley
where he held the title University Professor and Class of 1958 Professor of
Economics and Mathematics Emeritus. During his leaves in late sixties and
seventies he visited universities in Leiden, Cambridge, Bonn, and Paris.

His later studies centred mainly on the theory of differentiable economies where
he showed that in general aggregate excess demand functions vanish at a finite
number of points. Basically, showing that economies have a finite number of
price equilibria.

In 1976 he received the French Legion of Honor. He was awarded the 1983 Bank of
Sweden Prize in Economic Sciences in Memory of Alfred Nobel for having
incorporated new analytical methods into economic theory and for his rigorous
reformulation of general equilibrium theory.

In 1990, he served as President of the American Economic Association.

Debreu married Francoise Bled in 1946 and had two daughters, Chantal and
Florence, born in 1946 and 1950 respectively.

Debreu died in Paris at age 83 of natural causes on New Year's Eve, 2004 and was
interred in the Père Lachaise Cemetery.

`
LIST OF NOBEL PRIZE WINNERS IN ECONOMY`

**
Akerlof, George A.**

Allais, Maurice

Arrow, Kenneth J.

Aumann, Robert J.

Becker, Gary S.

Buchanan, James M., Jr.

Coase, Ronald H.

Debreu, Gerard

Engle, Robert F.

Fogel, Robert W.

Friedman, Milton

Frisch, Ragnar

Granger, Clive W. J.

Haavelmo, Trygve

Harsanyi, John C.

Heckman, James J.

Hayek, Friedrich August Von

Hicks, Sir John R.

Kahneman, Daniel

Kantorovich, Leonid Vitaliyevich

Klein, Lawrence R.

Koopmans, Tjalling C.

Kuznets, Simon

Kydland, Finn E.

Leontief, Wassily

Lewis, Sir Arthur

Lucas, Robert

Markowitz, Harry M.

McFadden, Daniel L.

Meade, James E.

Merton, Robert C.

Miller, Merton M.

Mirrlees, James A.

Modigliani, Franco

Mundell, Robert A.

Myrdal, Gunnar

Nash, John F.

North, Douglass C.

Ohlin, Bertil

Prescott, Edward C.

Samuelson, Paul A.

Schelling, Thomas C.

Scholes, Myron S.

Schultz, Theodore W.

Selten, Reinhard

Sen, Amartya

Sharpe, William F.

Simon, Herbert A.

Smith, Vernon L.

Solow, Robert M.

Spence, A. Michael

Stigler, George J.

Stiglitz, Joseph E.

Stone, Sir Richard

Tinbergen, Jan

Tobin, James

Vickrey, William

alfredslinks

**
**

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