Gérard Debreu

Gérard Debreu was a French-American economist and mathematician who gave general equilibrium theory a rigorous axiomatic foundation. He received the 1983 Nobel Memorial Prize in Economic Sciences.

General equilibrium theory: An economic framework studying prices and allocations that make supply and demand balance across multiple markets simultaneously. This was the central theory Debreu helped establish on rigorous mathematical foundations.
Arrow–Debreu model: A formal model of an economy with consumers, firms, and markets for dated and state-contingent commodities. It gives a comprehensive setting for Debreu’s equilibrium analysis.
Kenneth Arrow: An American economist whose work shaped social choice theory, general equilibrium, and welfare economics. Arrow and Debreu jointly proved a landmark general-equilibrium existence result.
Arrow–Debreu security: A security that pays one unit in a single future state and nothing in other states. Such securities illustrate how complete state-contingent markets are represented in the model.
Theory of Value: Debreu’s 1959 book presenting a rigorous axiomatic treatment of competitive economic equilibrium. This work became the clearest statement of his foundational approach.
Walrasian equilibrium: A set of prices and allocations at which consumers optimize and every market clears. Debreu formalized conditions under which this equilibrium exists.
Existence of general equilibrium: The mathematical question of whether an economy’s conditions permit prices and allocations that clear all markets. Debreu’s most influential results established existence under explicit assumptions.
Léon Walras: A nineteenth-century French economist who developed an early mathematical theory of general equilibrium. Walras posed the equilibrium problem that later formal work, including Debreu’s, sharpened.
Complete markets: Markets in which every relevant contingent commodity or risk can be traded. Completeness is a key assumption in the model’s treatment of uncertainty.
Nobel Memorial Prize in Economic Sciences: An annual international award recognizing outstanding contributions to economic sciences. Debreu received the prize in 1983 for integrating new analytical methods into economic theory.

Linked from 5 pages

First welfare theoremRelated: His rigorous framework clarified the assumptions behind equilibrium and efficiency results.